Just for your info, my USB UMTS stick (Huawei E169) will arrive tomorrow, and I plan to integrate Web access through connectionMgr. The necessary basics are already available, I will modify the dialup procedure mainly used for CF modems (which is done in /usr/bin/dialup.sh or so). This should be the easiest way to enable usual Web access as well as things like automatic downloaders.
If that works I will check whether the stick fits inside the device's backplane
And if that works I will have a Kindle that is not as fugly as the original one