First, if you're using windoze, be sure to open default.txt with WORDPAD (not notepad). After you open it in wordpad, you'll see something similar to what Harveystyles posted above. Any of the lines that start with a # symbol will not be run, that is just there to help people editing the file. Near the bottom you'll see something like this:
set cmdline "ppp.username=mobile@jamamobile ppp.password=telecom"
replace that line with something like this: (be sure to add your own username in place of the stars)
set cmdline "ppp.username=*******@sprintpcs.com msm_sdcc.msmsdcc_fmax=32000000 pm.sleep_mode=0 board-htcvogue.panel_type=0"
The above code is what I am currently using on sprint and it works great (after you run togga of course!)
If you don't know your sprint username, you can find it by pressing ##3282#
Hope this helps some people!
edit: BTW,
www.andappstore.com is a good place to get lots of .apk programs (not sure if somebody mentioned it yet or not)
edit 2: Glad you got it working Harvey! I guess it varies by phone? Mine didn't work until I put in that exact line above.