Here is what I did to get them working with the UTX roads. Please do so at your own risk though and back-up the terrain.cfg file in the main FSX directory. Find the entries below in the terrain.cfg file and add these lines. The guid#'s point to 4 different vector autogen object entries (the vector lights) that FTXG inserts further up in the file. I'm not sure if these guid numbers vary system to system, so you may wish to check. You can use whichever ID for whichever road, set the density, ect.. You can also add them to the rural roads (I didn't in my case).
[Texture.393] Name=UT_ROAD_3_T_URBAN guid={310896D3-A126-48b9-BDEF-416CAC59B368} Textures=UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTCD3TL_LM.BMP Layout=3_PLUS_4 StripWidthMeters=25 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={24A157E8-59BA-7748-AB32-7A688036A873} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=104255 Water=No
[Texture.394] Name=UT_ROAD_3_F_URBAN guid={320B8490-1CA5-4736-9622-3B837460821C} Textures=UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTAD3.BMP,UTCD3FL_LM.BMP Layout=3_PLUS_4 StripWidthMeters=25 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={24A157E8-59BA-7748-AB32-7A688036A873} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=104255 Water=No
[Texture.398] Name=UT_ROAD_2_B_URBAN guid={200F151C-1600-428d-868A-483E906C0A42} Textures=UTCU2.BMP,UTCU2.BMP,UTCU2.BMP,UTCU2.BMP,UTCU2.BMP,UTCU2AL_LM.BMP Layout=3_PLUS_4 StripWidthMeters=25 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={079F0A35-198F-AC4B-B5BF-BD27A1462736} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=103250 Water=No
[Texture.399] Name=UT_ROAD_2_T_URBAN guid={210896D3-A126-48b9-BDEF-416CAC59B368} Textures=UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTCD2TL_LM.BMP Layout=3_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={079F0A35-198F-AC4B-B5BF-BD27A1462736} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=103255 Water=No
[Texture.400] Name=UT_ROAD_2_F_URBAN guid={220B8490-1CA5-4736-9622-3B837460821C} Textures=UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTAD2.BMP,UTCD2FL_LM.BMP Layout=3_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={079F0A35-198F-AC4B-B5BF-BD27A1462736} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=103255 Water=No
[Texture.404] Name=UT_ROAD_1_B_URBAN_MAJOR guid={100F151C-1600-428d-868A-483E906C0A42} Textures=UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1AL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={81F596DE-70CF-DC43-BFCC-6F64A456DB23} (Medium road with light poles and telephone poles) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=102250 Water=No
[Texture.405] Name=UT_ROAD_1_F_URBAN guid={120B8490-1CA5-4736-9622-3B837460821C} Textures=UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTCD1FL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={1D64764E-9F03-894D-AA40-847233974C2C} (Small road with telephone poles only) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=102255 Water=No
[Texture.406] Name=UT_ROAD_1_T_URBAN guid={110896D3-A126-48b9-BDEF-416CAC59B368} Textures=UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTCD1TL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={1D64764E-9F03-894D-AA40-847233974C2C} (Small road with telephone poles only) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=102255 Water=No
[Texture.408] Name=UT_ROAD_1_B_URBAN_MINOR guid={7938B3BF-2CE6-4204-A1CB-B72382FC4D23} Textures=UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1.BMP,UTCU1AL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=7 FlattenMode=none FlattenPriority=21000 LandClassRemapType=none VectorAutogen={1D64764E-9F03-894D-AA40-847233974C2C} (Small road with telephone poles only) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=102250 Water=No
[Texture.412] Name=UT_ROAD_RAMP_T guid={12C2D8CD-71FF-48df-816B-63BA782DE639} Textures=UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTCD1TL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={079F0A35-198F-AC4B-B5BF-BD27A1462736} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=101250 Water=No
[Texture.413] Name=UT_ROAD_RAMP_F guid={22C2D8CD-71FF-48df-816B-63BA782DE639} Textures=UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTAD1.BMP,UTCD1FL_LM.BMP Layout=7_PLUS_4 StripWidthMeters=13 FlattenMode=flat FlattenPriority=21000 LandClassRemapType=none VectorAutogen={079F0A35-198F-AC4B-B5BF-BD27A1462736} (Large divided highway with road signs and generic signs and large billboards and median barrrier and middle lights) ExcludeAutogen=Yes RenderToTexture=Yes RenderPriority=101250 Water=No