Is there an AS3 library to create Illustrator files? OR do you have an example creating an AI file with AS3?
An alternative and very very last resort is to create a PDF with AlivePDF and see if Illustrator can import that but that seems like a hack and I'm concerned it will lose fidelity. I'm working on very hifi subpixel positioning here of text data. No offense to Alive PDF it may work fine.
There is an old trick you could try... if your output is on the stage at runtime you could use the print command and in the print menu print it to PDF.
It's good enough for quick prototyping and getting random generated patterns into Illustrator.