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.