Displaying static aircraft at different times and dates

I have owned Lago's Emma Field scenery for a while, and I am very impressed with the way that certain objects only appear in the appropriate conditions and times. I would like to do the same with static aircraft and static cars in my Harris Hill Gliderport scenery, if it isn't to horribly complicated. This is how I would like to have the aircraft appear:April-October, weekends, nice weather: private racing sailplanes, sailplane trailers, two-place fiberglass sailplanes, Schweizer trainers, towplanes.June-September, weekdays, nice weather: two-place fiberglass sailplanes, Schweizer trainers, one towplane.November 29-30 "Snowbird" Contest! Schweizer trainers, Bergfalke vintage sailplane, sailplanes from other clubs, towplanesJune 17-26, 2003, nice weather, 15-meter class National Contest: Oodles of racing sailplanes, oodles of sailplane trailers, many towplanes.I have started modeling the static aircraft in Gmax. I don't really want to do the fancy animatiions that Emma Field has, I just want to have some variety in the static aircraft on the airfield. Can I simply edit a few lines of text in the .asm file to get the desired affect, or is this going to require lots of programming? Thanks, Ryan the GlidiatorCaelum Oppugnabo! I shall attack the sky!Harris Hill Soaring Club Website:http://www.harrishillsoaring.org/