I finally got it to work - it turns out that my physical printer wasn't available on the Admin acct on the Compaq, breaking Redmon. A registry tweak later and now my iMac prints via DAVE.

However, sharing the DAVE PS printer via AppleShare doesn't work. No AppleShare client or LaserWriter 8 driver actually acknowledges the printer, on either the iMac or my LC. I tried "sharing" the desktop printer by copying it into a shared-via-AppleShare folder, and then pulling it onto the desktop on the LC, but printing anything produces "error -8940." Here is an article describing the error.