For people who don't have their own SDK, you can do this.
class AKFXPawnBase : public APawn //0x88C -> 0xC48
INT MultiJumpRemaining; /* 0x00000AE4 */
INT MaxMultiJump; /* 0x00000AE8 */
INT DoubleJumpZ; /* 0x00000AEC */
AKFXPawnBase* pLocalKFXPawn = reinterpret_cast< AKFXPawnBase* >( GEngine->GetLocalObject( AKFXPawnBase::StaticClass() ) );
pLocalKFXPawn->MultiJumpRemaining = 1337; //I don't think you need to do this, but w/e
pLocalKFXPawn->MaxMultiJump = 1337; //Generally... it's 2 but if you want to keep jumping
pLocalKFXPawn->DoubleJumpZ = 800; //Max :O U can log for original double jump z, which is 400 something...