Well, you are in luck...
I noticed that a lot of folks jump this rather critical step in hacking their AVIC. There are several threads on here where you can find them, but some require you to register on the site (and pay for it in some cases) in order to get the files in a timely fashion.
I have a hosted account with unlimited bandwidth, so I've decided to help out.
Username: avicuser
Password: Avic411
(The username and password are case sensitive)
You will find the F90BT files in RAR format (big thanks to Minifreezer). If you have files to other AVIC units, please contact me and I will upload them there for anyone that needs them. I am not sure how fast (or slow) this will be, but like I said it is unlimited bandwidth so they'll be there indefinitely.