I found a thread with instructions for mining Primecoins:
http://www.ppcointalk.org/index.php?topic=316.0summary of key points in the instructions:
In the Primecoin client, go to "Help" > "Debug window" > "Console" tab > type "setgenerate true -1" to use all of your cores or "setgenerate true 4" to use 4 cores, etc.
Type "getmininginfo" into the debug window to see your "primespersec" (mining rate)
If the primespersec is anything higher than 0, you are mining
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