Hey Matt,
So I ended up using the 04 plate that came with the CDL shifter. Made the install MUCH easier as you don't have to do an additional cutting on the original.
Ya I just used sheet metal screws drilled into the same holes the rivets were in. They have worked great.
Just a note, make sure you put a good deal of RTV down around the plate after it is installed... it will reduce cabin noise A LOT. Also it will help stop air from coming from outside through the plate. I didn't put any RTV down the first time, and the noise was really loud and it was COLD from the air outside coming in. I had to get in there about three weeks later to swap my CDL detection switch, so I put down a good bead of RTV around that plate and wow, it made a WORLD of difference.
Good luck with the install! It's pretty straight-forward. The hardest part is taking the center console out and then re-attaching the brake cable can be a PAIN!
Let me know if you have any other questions!