I have a wrench similar to Mellow's that I picked up at the Honda shop but have not used it yet. I got it as a replacement for one that fits over the end of the filter. That one did not have enough clearance to slip it on the filter. It was a generic from Auto-Zone I think.
Do make sure you buy the shorter oil filters. They are common and Honda uses them on several models but the longer ones will screw on OK but when you take the bike off the centerstand, the top of the stand may dent or cut the filter. See pictures in gallery under "oil filter trouble". I tried to cross reference filters when ordering and ended up with 2 or 3 long filters. Don't do that.
Brad