I released a MTA version back in January of this year that was compatible with FLA. The only limit that was not resolved was the ID limit relating to the 16 bit limit(IDs couldnt be over 32767). I am currently working on a new version and with Fastmans help we were able to resolve the 16 bit limit(FLA 4.1+). Based on experience making the standard MTA code compatible with FLA was rather easy, it mostly included changing hard-coded values(addresses usually) to dynamic ones as suggested by Fastman.
My release:
http://gtaforums.com/topic/839261-saxvcxlc-mta-compatible-build/
