I believe Den1 used pure MSM crystals in her hair products and she's one of the veterans of LHCF with gorgeous hair, both relaxed and natural. She no longer posts here and so I had a hard time finding her posts on this but she has a website here:
http://www.mydelouisenaturals.com/
ETA: I found her.
I wish y'all would stop changing your names
Some of us old folks cannot keep up. Her screen name is now Godsno1girl. OK, wrong links given (sorry). Still looking for one--or maybe I imagined all this.
OK, I'm back and then I swear I'll crawl back under the rock from whence I came coz I obviously don't know what I'm talking about. Couldn't find anything on Den1 using it in her conditioner. Not sure why I thought of her. I think there might be sth on the website of Distilpure (which I think I learned of from her that does say you can use it, and I somehow got them mixed up). Anyway, here's a thread where someone shared a recipe of MSM in a topical product:
http://www.longhaircareforum.com/showthread.php?t=17253
And another discussion that talks of adding it to products:
http://www.longhaircareforum.com/showthread.php?t=118563