Have you tried looking at Medicare's LCD for your area? Whenever someone has a question about how to bill Medicare, I always suggest the LCD's or NCD's, as they'll usually answer questions like yours. I just did a quick search of the LCD for my area and it deals with all kinds of codes mental health CPT's and HCPCS codes. I only did a quick look, but didn't see any modifiers listed that should be used for my area. Please check your area.
If you want to send me a list of codes via PM, I'll check our encoder Pro program when I get a chance, and that gives us details of each code, etc.