i also wana install j,b 4.2 custom rom n i dont know how..
but u can go into clockworkmod recovery.
1..install cwm auto installer from googe in which u can see ur model is supported just click on download cwm
2..reboot into recovery
3..when sony logo comes press and press and press presss back but untill u entered in recovery mode.
and tell me how to install jelly bean on it if u accomplished ur GOAL.