GameSages has posted details on how to use Quake 2 maps in Kingpin (thanks Billy "Not in the face! Not in the face!" Wilson). Here's the scoop:

• Download a Quake II editor like quark or qped.
• Load it up and open the pak1.pak in your baseq2 directory.
• Open the maps folder and right click on the ones you want.
• Choose export file and save the bsp in you kingpin/main/maps folder.
• If you don't have that folder make one, make sure you export the folder textures and place them in the kp texture directory.