I'd tell your doc that you've read some good things about
using mesalamine enemas in conjunction with oral meds like Asacol, and that you really want to try them, so will he please write you a prescript
ion. I'm including a link to an article from
Gut journal that outlines the effectiveness of using the oral + rectal approach with extensive UC (pancolits). I found it the other day b/c there's been a lot of discussion on the board lately about
docs who say rectal meds "won't work" for pancolitis. My personal experience told me otherwise, so I went looking for proof. I don't think you've said where your inflammation is, but even if its not pancolitis, this article at least discusses their effectiveness in limited UC. I'd at least skim it if I were you, and you could perhaps take it with you to your doctor's appointment.
As for other discussion with your doc, be completely honest about the symptoms you're experiencing.
Journal article in PDF form:
http://gut.bmj.com/content/54/7/960.full.pdf+html