tkane is using the volumetric light option also. That was improved in 5.1 to pickup color better and c4 doesn't have the second light thru trans option anyway. The translucency option isn't going to work in c4 either. I think what has worked is copying the same settings from color channel to transparency and glow. I think  the glow channel can work with this in c4. Kinda simulates translucency.

No need to think outside the box....
    Just make it invisible.