Basically the bans are stored as an array in Engine.AccessControl and the values in the INI file (in this case list of bans) simply populate this array like any other globalconfig variable. So there is no way to even move the bans into a separate file!
In order to do something more complicated like hooking it up to an external database you'll need to code your own server actor to do this.
UTAN actually stored the bans centrally on their servers and the server actor they wrote replaced the built in Engine.AccessControl with a version that checked the player's details agains this central database.
Since I assume you were looking for something that would syndicate to a database etc under you control I doubt this is what you were looking for but anyway UTAN is long dead so the point is moot.
Also I understand the project was bedevilled by technical performance problems (fundamental design stupidity of having hundreds of servers query the central db instead of distributing it p2p) and political problems of the nature of which I'm sure you can guess (picture a load of power hungry self-appointed "super admins" arguing over the keys to the biggest UT2004 syndicated bans system...)
Further as part of the power hoarding attitude the UTAN server actor itself was closed source (i.e. they stripped the unrealscript which is unfortunate because we could otherwise cannibalize parts of it for KF) and was reputed to do a lot of dodgy things beyond its supposed remit like giving the UTAN admins powers on _your_ server.
</Rant about UTAN>
We run 8 KF servers now so I have every intention of developing a simple server actor that syncs bans with a shared MySQL database, with extra points for a PHP web frontend ala sourcebans.
Notwithstanding a few complications like ensuring performance, DDoS-proofing it and the fact that the unreal mysql client is a buggy PoS I'll probably have something to open source within the month.
Of course if anyone with the expertise is willing to help out or indeed someone far more competent wants to take this idea off my hands please do get in touch
