Anything involving level geometry cannot be made transparent. You can build a map entity, however, but you can only have the entire object as one set level of transparency. For full control on transparency, use a model with a TGA skin where the TGA has alpha channel.
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
