Not really an adjunctive therapy... more like an alternative form of conventional treatment for post-radiation dry mouth.

I had to do the leg work on this, but it paid off. Although not generally available, I was able to show my MO published trial results and convince him to write a prescription:
Pilocarpine 1% solution by volume, 1 teaspoonful PO bid (swish/spit after 2 minutes)

The advantage of the mouthwash version is that it is instant acting, reportedly long lasting, and has none of the side-effects of the oral (pill) version. The studies I found online had partipant results claiming 12-36 hours relief from just one use of the mouthwash solution. My results were not as good (~ 6hrs), but enough so that I have been able to cut my oral Pilocarpine use down to one 5mg pill/day, and sleep through the night (no more frequent urination and phlegm buildup because of the oral Pilocarpine).

There are a few downsides to the mouthwash though.
1) You'll need to find a compounding pharmacy that will work with you to come up with a palatable formulation. A standard pharmacy can't fill the Rx.
2) Liquid Pilocarpine has a short shelf life, so you won't be able to purchase more than a 45-60 day supply at a time.
3) It's expensive...and most insurance doesn't cover it (yet). Shop around, as price varies considerably.

I hope this helps someone... it did me!

-Bob