How to Mod & Edit Cutscenes in SR2

Can Someone tell me how to mod and edit cutscenes in saints row 2, i've seen masakoteam and mrsaintsgodzilla21 do it before, so how do i do it??
You must extract vpp files first... Like "cutscene.vpp" and "common.vpp". Then use some tools to check up the files that the cutscenes contains, for example, the Boss uses a Shotgun instead of a Beretta in Julius mission.