Several routers support the Pantech UML290, but I don't know of one that supports the LG modem. The Nexaira Business Class II, the Wifi Ranger, and several routers from CradlePoint support the Pantech. I recommend searching the EVDO forums for discussions on this topic. Read what others have experienced. I've been using the Nexaira router with generally positive results.
Having said that, do you really want to drop your wired connection from Comcast? 4G LTE has great speeds--even faster than many cable connections--but the 5G/10G cap can bite you, particularly if you need to perform software updates.