Authentification plugin

[FakeTruth]

Well, I can, but it's not possible to disallow a player that connects.. yet.. (I hope)

Yes it is
Use the E_PLUGIN_LOGIN hook and the OnLogin( cPacket_Login ) function. Return true to kick the player.

Player:BanPlayer/Player:KickPlayer should be installed. :p

Yes it should, lol. Better make this my top priority then.

EDIT: Btw.. If you want it non-MySQL, it would be usefull to install a word compiler, like MD5, else you could see everyone's pass.
LUA doesn't normally have MD5 installed.
But you should also need then a XML parser... For saving on a save way. :/

I already have a md5 hasher for MCServer, just not exposed to Lua yet. I don't see why you'd need an XML parser though, you could use the ini files.