You can package it.
function secureClientCmd_ClientJoin(%nn, %cid, %id, %v1, %v2, %v3, %v4)
{
%nn being net name, %cid being client object ID, %id being the BL ID, rest is stuff like score, trust, admin, minigame. Didn't feel like figuring out which was which.
It gets called for every client when you first join, as well as for every client that joins after you.