[T-Mobile LG G2x] Scyth3:
I've updated your steps with a bit more info (thanks for the steps by the way!). I've also merged them with the OP's so it's a bit more clear cut. I had already rooted my G2x via ADB, and was running the latest CM7 nightly. I just wanted the latest baseband. Also I was running LG-p999dw, not LG-p999dwp but based on mmapcpro's post, it should work for that one as well.

Computer Software Setup -- Do First

Prior to flashing your phone, setup your Windows computer (I tested on Vista and Windows 7) with the following software:

1) Copy the NVFlash app, download and also install the APX drivers, etc. If you've yet to flash CWM to your phone via NVFlash, now is a good time The thread to do that is here

2) Download the KDZ file

3) Download the LG KDZ app from here: http://xdaforums.com/showthread.php?t=810271

4) Extract the files from the .7z (7zip) compressed archive to a directory on your desktop (I named my directory LG KDZ).

4) In the extracted LG KDZ app folder, run and install the msxml.exe. This is important.

5) Download the T-Mobile G2x Android USB driver from LG.

6) Install the LG Android USB driver you just downloaded

7) Download the LG Mobile Support Tool

8) Install the LG Mobile Support Tool you just downloaded.

Now, you've installed the LG support software drivers, USB drivers, downloaded NVFlash and LG KDE's tool, etc. I HIGHLY RECOMMEND that you should restart your computer before continuing. All of the stuff above worked fine on both my Win Vista computer, and Win 7 box.

Phone - Ready to flash

1) Nandroid backup your current CM7 nightly.

2) Restore to stock using TGA_Gunnman's nandroid, wipe data/factory reset immediately AFTER restoring stock and prior to turning phone back on

3) Turn the phone on and skip google login

4) Enabled Debugging mode

4a) [Optional] Unroot with superoneclick. I did not do this step since I rooted it manually via ADB. My phone had no problems updating.

5) Turn the phone off and pull out the battery

6) Start up nvflash

7) Press and hold volume up and down keys simultaneously, waiting a few more seconds and then plugg in the USB cable (USB cable should already be connected to PC's USB port)

8) Select "Flash Stock Recovery" and continue to hold the volume keys down until the flash completed and said "press any key to continue"

9) Pull out the USB cable, release volume keys, re-insert the battery, and power up the phone, again skipping google login

10) You should now be on the Android desktop on your phone. Plug in the USB cable to the phone.

11) Open the KDZ program (you should've installed msxsml at this point since it's in the steps above these) then keep the settings: "cdma" and "DIAG" alone.

12) Select the browse and select the V21E_00.KDZ file you downloaded in the previous steps.

13) Click on "read phone information" at the bottom left corner of the program.

14) Click on Upgrade Start button on the dialog that popped up.

15) Change the country option in the popup to "different country" and change language option to "English".

16) Click Ok and this launches the LG updater and will push the update of GB to your phone. LET IT COMPLETE WHATEVER IT'S DOING. Pulling out the USB cable while it's working will most likely brick your phone. Your phone will automatically reboot and install the update by itself, no work on your end necessary. It will look like it's taking awhile, but just let it do its thing. You'll also hear your USB connection in Windows toggle on and off quite a few times. The entire process took 6mins for me.

Congrats, your phone should now be back to stock with the new baseband and GB update.

Now, to restore back to your rooted CM7 from before and keep the new baseband:

17) Turn the phone off and pull out the battery

18) Start up nvflash

19) Press and hold volume up and down keys simultaneously on the phone, waiting a few seconds and then plug in the USB cable (USB cable should already be connected to PC's USB port)

20) Select "Flash External Clockworkmod" and continue to hold the volume keys down until the flash completed and said "press any key to continue"

21) Pull out the USB cable, release volume keys, and re-insert the battery.

22) Boot into CWM by pressing and holding the volume down button and power button simultaneously until the 2nd splash screen appeared (ANDROID in green letters).

23) Restore your backed up CM7 nandroid that we did in step 1, fix permissions, wipe dalvik cache, reboot phone.

You should now be running CM7 on the new baseband. Hopefully that makes it a bit easier, since I was cobbling things together as I did it.