Merkur,

The way it should work is that it's no different from EVE's normal gameplay, in other words players won't be logging in to a separate PvP server. What happens after the server request would be transparent to the players -- basically, behind the scenes CCP would divert additional resources/servers to the given solar system(s) that they've been notified will be contested.

It's not an ideal solution for the lag, but it's an option they've made available to the players.