Never mind just found out the n900 simply cannot have USB OTG since it can only take in electrical input.

Or in other words, the n900 does not support USB host mode because it cannot supply its own power to read the Device (flash drive) on the other of a cord, it can only take in electrical input. So it's never gonna happen.

EDIT: Just saw someone said it was possible, and he was working on it...but progress seems to be lost...