I'm pretty sure that a 2.3.4 neo rom, or custom rom will work on a neo V but the camera certainly won't work because of the 5Mpxl of the neo V sensor compared with the 8Mp of the neo. But the harware is the same.
(I'm gonna try to stay calm, but I can't promise anything)/
A few things:
1) MT15a is NOT "the first neo", it's the american version of Xperia Neo (vs. MT15i which is the european version), the only difference is in the radio chip, meaning you won't see a difference unless you're in a european country.
2) There's a huge, let me repeat that HUGE section of this subforum called "Xperia Neo Android Development", there you will find all the custom ROMs for Neo.
3) If you (clearly) don't know what you're doing, I'd suggest you stay away from custom ROMs until you read some more here on the forum, for christ's sake, read both the stickies and the FAQ's a million times until you've memorized them by heart.
4) Why the hell are you reviving a year old thread??
P.S.: I find it ironic that your reason for editing your post was "fail", considering the entire post and your lack of knowledge is an epic fail!!