Run a search on it -- you'll find your answers.
My trainer swears by it for getting rid of loose skin from weight loss pre comp. You can inject intra muscular or subQ. She also advocates mixing it up w/ Thiomucase (or Preparation H) and rubbing it in topically, putting on a light layer of DMSO as a carrier and wrapping it all up in saran wrap before doing cardio to get the shredded, skin tight comp look. Like Yohimburn, I think it prob works best if you are already low bf.
The jury is out on pain level of the injections -- i've done both w/ a regular needle in the glute & also w/ an insulin needle as well as the topical. Didn't bother me.