A couple of months ago I retrofitted an Alfine hub to my touring bike and used the Alfine chain tensioner... the Shimano instructions actually give guidelines for running multiple chainrings and how to size the chain, etc.

Also, the Alfine chain tensioner did not work well with the 1/8" chain - the chain was lightly rubbing on the sides of the tensioner, and I lost the option of using the (still installed) 28 and 46 tooth rings. I have run the bike several times with the other rings, but I just swap it over by hand as I removed the front derailleur and shifter when I installed the Alfine hub.