Funny you should ask about that...
Some photos here:
http://www.flickr.com/photos/colin_young/tags/template/
Basically, I took a piece of 3/4" plywood and screwed a cleat parallel to one edge (actually, it was a jig left over from another project). I then measured the distance in from the side of the cabinet to the center of the leg holes. I also measured the distance the legs were set back from each of the front and back edges of the cabinet and the distance between the centers.
Using those measurements I drilled 4 holes (2 for the backset from the front edge, and 2 from the back edge) using a 12mm bit on a drill press, parallel to the cleat (remember to measure from the inside edge of the cleat). It's critical that the holes are perpendicular.
Then I tested the fit of the legs to make sure I had the spacing correct. Once that is confirmed, all you need to do is put the cleat up against the side of the cabinet and line up the edge of the template with the edge of the cabinet and you're ready to start drilling (The backset is appropriate for the toekick being the same distance back as for a base cabinet, but you might find that the cabinets seem a bit unstable that way and decide to move them forward a bit, in which case just clamp it where you want the holes, making sure to avoid the cam holding the sides on).
If you can't find a 12mm forstner bit (not many places stock them), you can use a 12mm brad-point. I found the correct depth by trial-and-error, then used painter's tape wrapped around the bit to mark the depth.
Hope this helps. At some point I'd like to write up a proper tutorial with photos inline and additional diagrams, but this will have to do for now.
Colin
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