using a HP JetDirect for LaserJet III with Amiga

[adolescent]

DLC, like TCP/IP, IPX, etc. is a network protocol.  Sorry to say I've never seen DLC on the Amiga.  (And, it's mostly abandoned, according to Wikipedia it's no longer available in Windows even.)  

Edit:  You might be able to re-share the printer out using Unix printing support.  I know it's possible on 2000 Server, not sure about Professional.  It should be listed as "Other File and Print Services" or maybe Unix printing in the Windows components list.

[adolescent]

All this for a Laserjet III!?  IMHO, you should just look for a newer printer.  HP 4M and 5M are very reliable, and can be had for about the cost of your JetDirect card + shipping!