Here is a good place to start. My partner teaches for this company, and I went to a week long LTI/Cadzone mapping school held out in Dennis by SRR. I liked it, it makes me $ on the big clock as well nowadays.
The MSP just ran the full course (Basic, Advanced & Recon) in February and October this year, by IPTM.
I know there are others but the IPTM program is a nationally recognized program. I know a few who have gone elsewhere then werent as well prepared for their ACTAR exams. Some took the IPTM but never used it and its something you definitely use or lose.