As the title states, I am trying to find a way to map the checklist button on the Cirrus dash to a button on my flight stick but am stuck. I can't seem to find the variable for it. Can anyone help?

Did you try the MSFS developer mode?

When this is active, open the "Tools->Behaviors" dialog. Then click back into the sim, hover your mouse cursor over the button or lever that you are interested in and press Ctrl & G. Now the behavior code for that button should show up in the behavior dialog. At the bottom of all the components there usually are the mouse events, things named ...LeftSingle... Drag... etc. Those contain the code that is executed when you click/drag/whatever that button or lever. That is what you have to replicate in AAO.