[preamble: this was nicely formatted but now the forum won't let me post any helpful links or things that look like e-mail addresses, like DUN credentials. My account is about a year old but I guess I don't post enough. If a moderator would like to fix the formatting, please be my guest, I've bolded those parts I had to clobber.]

Thanks for posting all the helpful hints here folks. I've been learning stuff here for years.

Finally figured out how to use my LG VX-9100 for tethering (EVDO) based on stuff I found here and my own poking around. I believe in the end the required steps were:

1) use BitPim to modify the third byte of paramtable1.fil from 00 to 20 as per:

the "LG VX5500 another way (also works for pre-paid phones)" page in the howardforums wiki.

from what I can tell this enables editing on the phone. Aside: for Fedora 16 (x86_64) the dependencies needed for the BitPim RPM were gtk2.i686, compat-expat1.i686, and clearlooks-compact-gnome-theme. I found 'hexedit' to be a good hex editor.

2) enter phone programming. Open the phone, 'dial'
Code:
##PROGRAM9100
and press send. Type all zeros for the access code.
2a) Go into Data ... MIP Setting ... NAI Setting ... and make sure all 4 of the settings there are
Code:
your-10-digit-# -at- vzw3g -dot- com
The 'DUN' settings on mine had 'dun -dot vzw3g -dot- com in them. With these set to the 'dun' variant (as came down with programming) the connection would succeed, but I'd get a captive portal redirect to:

https dunsp -dot- vzw -dot- com

and get the error:

This device is currently not authorized to access Dial-Up Networking services, please contact your wireless service provider for more details.
I almost called PPC per the general FAQ here, but it wasn't needed, this was a handset issue.

2b) Back out of those menus. I think it will power off if you made changes. Power it back on.

credit: I got the general idea about this potential mismatch from here:

the "DUN page in the zaksenterprises wiki"

though it's not directly applicable to this phone.

3) connect to computer with USB cable

4) configure software. I'm using Fedora 16, so I configured a Mobile Broadband connection with nm-applet, and used the default Verizon settings, plus:
4a) Dial:
Code:
#777
4b) username:
Code:
your-10-digit-# -at- vzw3g -dot- com
4c) password:
Code:
vzw
4d) give the connection a name
4e) right click on nm-applet and enable Mobile Broadband connections.
4f) Then just left-click and select the connection you made. The phone dials just about instantly and will display a send/receive meter on the screen.

If you want to see how much data you're sending, you can run:
Code:
ifconfig ppp0
and it will show you RX bytes and TX bytes. I found it wise to go into Firefox and disable automatic loading of images. I'm on the 1200-minute plan and don't want to use it up too quickly. I just have this setup for emergency purposes now, but I'm glad to have it! I really love this phone - some day I'll give in to smart phones, but not until they're as secure as my [tethered] laptop. Some other day I'll try bluetooth tethering and tethering my rooted Nook tablet.