How do I change the DNS settings on Pace 5031NV?

You cannot.  You will either have to put a router behind the 5031NV (aka the "RG" or "Residential Gateway") and program your DNS choice into it, or you'll have to set the DNS manually in all your client devices.

All of AT&T's RG's have the DNS locked to AT&T's DNS servers.

Thank you for the quick response. Would you be able to walk me through how to set this up with the Linksys WRT160N V2? This was my old router before switching to AT&T.

For some general instructions, please see post 2 in this thread.

So this is why my connection is so badly lagged. ATT has slowed everyone down by forcing us to use slow DNS servers.