I took off the top slide of the cross slide (the one that can be adjusted for various angles. Then I took a 3"x3" right angle plate and mounted the slide to it. Then a small drill press type vise was mounted to the slide. It feeds in all three axis.
Don't expect to be able to take too deep a cut with it.
Total cost was about 40.00 (including a pretty nice Palmgren vise)