At the current moment I have not created any walkthru's for setting up H&D for multiplayer... though I plan to soon! Below is a list, as promised, of all the other sites with related sections. If you also have a site with a related section, please submit the link to me and I will add it promptly. Thanks!

HDRC: Starting a Multiplayer Game - Written by Lickshot
Pictorial walkthru, helps in understand graphically what each step should look like.

H&D2 Unofficial Site: Multiplayer Guide (H&D/Datadisk) - Written by Sniper
Comprehensive. This walkthru has one glitch, it indicates to get out of the game by hitting Ctrl+Esc—but in H&D on my computer it didn't work. Alt+Space does however. =)

Hidden&Dangerous Page: Setting up on-line play - Written by Scarface
One of the oldtimers of H&D's description of how to play online, and a good player too!