No Pointing a Subdomain to the wiki won't o the trick. maybe for small changes to fo but not for big things.
What is needed is:
--> for developers
First of all, especially if you have serveral modified files, you want something to upload them and manage the revisions of the files --> a scm like subversion or git is needed,
Something to document the mod etc --> a wiki page
a possibility to upload packages (like here in the forums)
Access controll, you want yourself and other developers be able to change the files but not every user
--> for users
a list of all modifications with ability to see if the mod is active developed and for which version
a possiility to submit the author bugreports or problems without having to search through 5 pages of posts in a forum.
much can be done by improving this forum and the wiki. but it dont seem like anyone does it here.
Yesterday i created a small proposal how i would like to have such a website, so here it is
http://fengforge.org/