the bars you got are for use with buffing wheels, not polishing bonnets. if you have a right angle buffer, and the spindle is 5/8-11 threads then you should look at getting this adapter.
http://www.caswellplating.com/buffs/grinderadapter.html
and some spiral sewn wheels as well as some loose cotton wheels. at least 1 of each. the size will be determined by the speed of your buffer. let me know and i can recommend better what to get. the problem with wool bonnets is they are not turning fast enough on the side you use. but on a wheel you use the face or outer diameter so the surface speed is greater. this will cause more heat when applying the compound thus melting it to the wheel. give me info on your buffer and i can get you going in the right direction since i use a combo like that often.