...As for which dremel disc to use, well, all of them are about the same thickness, which is thicker than the USGA rules allow.
The maximum groove width defined in the Rules of Golf is 0.035" http://www.usga.org/rules/books/rules/appendix_II.html
A Dremel #409 wheel is 0.025" thick and can cut a conforming groove http://www.dremel.com/productdisplay/bit_template.asp?SKU=409
With the proper fixture, you could also probably use Dremel bits #105, #108, and #111.
http://www.dremel.com/html/products/accessories/carving.html
Burgess
