http://forum.mikrotik.com//viewtopic.php?t=5756

Not sure if this is the one, but perhaps the most useful I have read on this forum. Freeradius 1.1 has the Mikrotik dictionary built in so you can skip that, but the rest looked right.

Post here if you have a hassle. Hey maybe log your steps and create a new tutorial! Maybe this one will find its way to the wiki.