Yes, the old one's still in the repo. In fact, you won't ever -lose- it, because you can -always- get old versions from the repo. Just remember that its version 3.x you need.
Also, you don't need it. You should flash the RootFS image you have via the Nokia flasher, then boot your N900(which will have the version of BackupMenu you had when you made the image) into BackupMenu, and restore the Optfs.
If you -can't- get the rootfs to flash properly, then you have a problem, the same problem that caused me to change.

Also, erm... To be fair, the only difference between the "old" backupmenu and the "new" one is that it's running in a ramdisk. All the old code(aside from console, which I took out because it was too -big- to read through when debugging) is still there. And the old key-commands still work. The menu-option text lines are just commented out.
However, none of the other options -work-, because of missing files.

Also, I don't think ssh or anything that relied on the USB Network actually worked; I copied that code from RescueMenu and didn't understand quite how to make it all work.