If the phone is rooted, most custom ROM's don't support the hidden menu a carrier ( like Boost ) will use to walk their customers through to activate !!
To activate, put FF19_Stock on the phone ( via Odin ) and use Halfass ROM !! After activating, you can use any ROM you like !
Odin (Return phone to Stock/Factory)
( use FE16_Stock or FF19_Stock )
[ROM][GB 2.3.6]HalfAssRom 2.1 - Stock on EXT4!