I'd say you build your own working proof-of-concept, then when it attracts attention, get some of the more handy players to help out.
What concerns me here is that the "lead coder" is N/A. In my experience, coders provide the major impetus for a mod, since they are actually the people who "get **** done" - and since the designer is the guy with the vision, how things should work out, he/she should be the coder as well (otherwise every disagreement between the two is going to kill the mod immediately).
The mods that work actually have well-working
teams (e.g. Fall from Heaven, Dune Wars) usually have a lead designer/coder + a lead graphics guy and various people that contribute irregularly over time (often even code snippets).
So if you really want to make this a) a big mod and b) one as a team effort, make sure that you're the coder who ultimately commits the changes to the code (even if you restrict yourself to XML coding etc.). Also, read
this, it is an excellent guide for planning a mod in general.
Cheers, LT.