How do I get the initial server spawn to be in a different world?

Okay, I've made a new world with Multiverse-Core (Named "defaultworld", unsurprisingly) and I wish for players to first spawn in "defaultworld", as opposed to "world" as they do currently. (I'm using "defaultworld" because "world" is very difficult to use custom generators on. >,>)

Basically, every time a player logs on, throw 'em in "defaultworld"'s spawn point.

The plugins I'm currently using are as follows, but the server is in early development, so more will be added in the future:
> AutoSaveWorld (Backup plugin)
> PermissionsEX + ModifyWorld + ChatManager (although I only really use the first two)
> CleanroomGenerator (for Multiverse support)
> Multiverse-Core + Multiverse-SignPortals
> PlotMe
> WorldEdit + WorldGuard

If I need to add another plugin to do this, then I shall.

Also, to prevent people from giving the wrong answers, here are thing's I'm NOT trying to do:
> Change the spawn point in "defaultworld"
> Change the spawn point in "world"
> Add a /spawn command

 

NeonJ
There are multiple plugins out there that can set a "FirstSpawn" point. I'm not familiar enough with Multiverse to know if it has an option to do this built in.