I have been toying with it and still no luck ,heres what I have:
C:/Program files/Steam/Steamapps/Email/Half-Life/Weaponspatch2.2
This allows the game to be shown in third party mods.
Inside the weapons folder there are:
cl_dlls dlls
logos maps(which btw is empty)
save cfg
liblist.gam pako.pak
voiceban.dt
I also tried copying the weapons folder to the e-mail folder and no luck. Even when the HL splash page comes up and I try to create server, the only option I get is random maps. Gmdm2 is not an option. So I let it generate a random map and tried changelevel gmdm2, then crashy-poo!
I hope this helps you figger it out Gollum. I sure would love to look around that map. If worse comes to worse, you could port it over to HL2 (whenever that year is that they release it now due to certain recent events at valve). I'm sure the new engine could handle it.
Note: I notice that each authorized val;ve mod has a file called ".gcf" in the steamapps folder. Perhaps this needs to be incorporated into the WP dll????(Who knows?)
Good Luck,
Juim