It doesn't sound like mission impossible :] However it does require a lot of work. (Connection checks, synchronization, database access optimization...)
i think that MySQL support would be VERY nice - i understand it's a lotta work but it would be another nice feature that'd make IOFTPD all that much more pimped out
maybe http://sourceforge.net/projects/tcl-sql/ will have what you need. It looks like it would be useable within ioftpd itself if yuo know a little bit of programming.