Connecting to the internet using an LG eNV cell as a wireless device.
 

Getting kppp to recognise the device was shamefully easy, and getting a connection worked like a charm. Verizon doesn't care what software you use to connect, but I kept getting disconnected after 2 minutes or so.

Well, I posted a thread here, and found very few people had experience using a cell for a wireless device, or at least very few responses. I asked friends, and a linux guru I know in England, and no one could figure the problem out. Finally, I started digging around in /etc/ppp/options, and found the following two sections that seemed to be a likely cause for the issue:

# If this option is given, pppd will send an LCP echo-request frame to the
# peer every n seconds. Normally the peer should respond to the echo-request
# by sending an echo-reply. This option can be used with the
# lcp-echo-failure option to detect that the peer is no longer connected.
#lcp-echo-interval 30

# If this option is given, pppd will presume the peer to be dead if n
# LCP echo-requests are sent without receiving a valid LCP echo-reply.
# If this happens, pppd will terminate the connection. Use of this
# option requires a non-zero value for the lcp-echo-interval parameter.
# This option can be used to enable pppd to terminate after the physical
# connection has been broken (e.g., the modem has hung up) in
# situations where no hardware modem control lines are available.
#lcp-echo-failure 4

Neither option is commented out by a standard install, so I figured it couldn't hurt to try commenting both options out. Eureka! I wound up with a very stable and sturdy connection that never times out, and is nearly as fast as I could hope for with DSL (which isn't an option where I live).

I know, hardly earth-shaking news, but it was a sticky problem for a while. Too many years of using some Other OS had made me forget at first that almost any problem can be fixed by digging into config files if everything else fails.