If you want Bodom tone then I wouldn't bother with a neck pickup, there's a reason the signature model doesn't have one. As for a pickup, Laiho's used passive EMGs (I think EMG HZ-H4s) with an afterburner. He's also used the Seymour Duncan Blackout.
Currently he's using his signature EMG pickup, the EMG ALX.
Depending on what amp you have, it may be a better idea to upgrade that instead of intalling a new pickup.