[millerhifi]

There isn't any configuration that you need to perform on your end with the treo 600. As long as it is properly set up for "wireless Internet" (dial up) and "Wireless Internet Express" (gprs) on Cingular's end you should be good to go. Simply inserting your Cingular SIM card into the treo automatically sets the network settings for wireless data capabilties.
From your launcher screen select prefs and from the pulldown menu (right top corner) select network and you should have 2 options pre configured at the "service" pulldown options, Cingular Express or Cingular. Select Cingular Express (gprs) and tap "connect" at the bottom of the screen. If properly configured on Cingular's end it should connect and show you 2 green arrows above the signal strength meter or select Cingular (dial up) and tap connect and you should see 2 black arrows above the signal strength meter. That's it, you can open the web and surf from there.
On a side note, who ever told you that Cingular does not support the Treo 600 and that you should seek help from the developers forum is full of it!