Correct me if I'm wrong, but I believe the older iPods used 2.5" laptop style HDD's and the newer ones use micro drives. I think the only ones that use nand flash are the Nano's.
I could be wrong because I've never owned an iPod, but if I'm right, there's no way to put a 2.5" drive nor a micro drive into your phone.
There is a company (PPCTechs) who upgrades flash ram and rom size in xda devices, but their site shows no upgrades available for the
vogue.