[T-Mobile myTouch 4G Slide] Blue6IX:
This information is not enough to be able to build a flashable-zip file to let you flash an update to another providers network.

In Sense for our device, the APN configuration settings are in an XML file which is compiled in framework-res.apk

When I decompile the framework-res.apk and open the XML file ( called apns.xml, located in the /res/xml/ directory of framework-res.apk ) here is what I have for T-Mo:

<?xml version="1.0" encoding="UTF-8"?>
<apns version="8">
<apn carrier="T-Mobile Data" apn="epc.tmobile.com" mcc="310" mnc="260" type="default,supl,admin,dun,hipri" />
<apn carrier="T-Mobile MMS" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="260" type="mms" />
<apn carrier="T-Mobile US 250" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="250" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 660" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="660" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 230" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="230" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 310" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="310" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 580" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="580" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 240" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="240" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 800" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="800" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 210" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="210" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 160" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="160" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 270" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="270" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 200" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="200" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 220" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="220" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="T-Mobile US 490" apn="epc.tmobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" mcc="310" mnc="490" type="default,supl,dun,admin,mms,hipri" />
<apn carrier="中華電信 (Internet)" apn="internet" mcc="466" mnc="92" type="default,hipri" />
<apn carrier="中華電信 (emome)" apn="emome" mcc="466" mnc="92" type="default,hipri" />
<apn carrier="中華電信 (MMS)" apn="emome" mmsc="http://mms.emome.net:8002" mmsproxy="10.1.1.1" mmsport="8080" mcc="466" mnc="92" type="mms" />
</apns>

As you can see, that AT&T information will not be enough to cover the range of data that needs to be supplied in order to swap the XML file over.

Not having an AT&T account or device, for right now my hands are tied until someone can supply me with the information necessary to be able to properly fill out this apns.xml file in framework-res.apk

The upside is that framework-res.apk is finished as far as graphics go on the ROM, it was one of the ones I made sure got handled for the 1.1 update, so it'll be easier to make the flashable update when we figure out the information. I won't have to keep altering the file for other changes and having you reflash it.

Sorry, I wish I could do better for you.

If our APN information was built from the apn file most devices have in /system/etc it would be a different story, but that's not how Sense works on this device.