I'm just posting this and self-answering it for posterity's sake.
I looked around the internet and couldn't find an answer, but was able to get around it. So I thought I'd throw it up in case anyone else searches for it.
When building an AIR mobile app from FlashDevelop and coming across this error:
Error occurred during initialization of VM
Could not reserve enough space for object heap
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
Compliation failed while executing : ADT
APK setup creation FAILED.