Neo's Retextured Vice City is basically a pack containing enhanced textures but like said it isn't really compatible with VC:MP or at least I couldn't run it when tested, probably need a downgraded exe or so. Or you could locate and export all the modifications he made into gta3.img because that's where the real changes are, the rest of the txd's outside gta3.img are just borrowed from different authors and tbh aren't even that high quality. But that is quite a lot of work. Until someone is willing to do that I suggest you install Hanney's VCVE pack.