I'm not really qualified to give advice but I'm interested in the same and here's what I gather: it depends on what level you want to do this work at. In the best case we would have both a PhD in clinical psychology and an MD with pharmacological specialization; then we would be fully qualified to do clinical/therapeutic work with patients/clients as well as possess the qualifications to administer the psychedelics.
If I were to go into this field it would probably be as an "alternative medicine" practitioner, though current laws of course forbid that. I don't have interest in pursuing a PhD in clinical psych unless that's absolutely necessary; instead I'd want to combine traditional knowledge about conducting effective healing ceremonies with the latest research, and of course obtain the appropriate degree to allow certification.
Now I'll refer you to people who are established in this field and have offered advice for people that want to make a career out of psychedelic study or applications.
Dennis McKenna (from an interview at Erowid)
MP: Have you any advice for current students of Ethnography/Anthropology/Chemistry?
DMK: Find a specialty and get very good at it. If you want to do research on psychedelics, don't go looking for a program where you can do that, because there aren't any. Instead you have to make your own program, go through the back door, so to speak. Again, this is where the right mentor can make all the difference.
Here's Dr. Shulgin's answer to a similar question except from someone who wants to go into psychedelic botany:
http://www.cognitivelibe...nce-how-to-prepare.html
Here's Charles Tart's advice to grad students interested in consciousness research:
http://www.paradigm-sys....ctt_articles2.cfm?id=56
Also have you read "The Secret Chief Revealed" by Myron Stolaroff, about the underground psychedelic therapist Leo Zoff? It's well worth checking out. It's free at the MAPS site,
http://www.maps.org/freebooks.html.
"...I didn't know that Cheshire cats always grinned; in fact, I didn't know that cats could grin..." - Alice's Adventures in Wonderland