Hot on the heels of this morning's full and permanent G2 and Desire Z root, XDA-Devs members (apparently headed by grankin01) have released a similarly full and permanent root for the T-Mobile myTouch 4G. In fact, the method is very nearly the same, in grankin's words:

unforgiven512 [who contributed to the G2 root] deserves most of the credit for this tutorial as all I did was rewrite this tutorial in my own words (while looking at his in another window), edit the kernel module, and paste links to it and the hboot file with this tutorial. Also, thanks to adwinp for the instructions on hexeditting the kernel module to make it work with our devices.

This was a collaborative #g2root effort, primarily involving scotty2, tmzt, IntuitiveNipple but also many others!

Just as with the G2 root, this method is riskier than some of the other methods we've seen before. It relies on Paul O'Brien's VISIONary, a few adb commands, and some console work to achieve the root. Full instructions:

First make sure you have visionary installed and download these two files:

http://www.megaupload.com/?d=A03YMPQK

http://www.megaupload.com/?d=NN5726Z8

Pre-OTA module: http://www.megaupload.com/?d=G400FOFB

Here are the md5sums for the modules and hboot: http://www.megaupload.com/?d=CFSHDJS1

Fire up your device and run visionary.

adb push the two files you downloaded to /data/local on the device:

adb push wpx.ko /data/local and adb push hboot_dhd.nb0 /data/local

Open up a terminal on the phone or thru adb shell and gain root (su + enter).

Type insmod /data/local/wpx.ko and press enter. You should get an error stating "function not implemented" this is what you want

Then type dd if=/data/local/hboot_dhd.nb0 of=/dev/block/mmcblk0p18 and hit enter. This command can turn your phone into a very expensive paper weight. Pay attention to what you are typing.

If you are on terminal on the device close it out. If you are on adb shell don't worry about closing your session.

Run VISIONary again to lock in root. Fire your terminal back up and type sync and hit enter.

Wait a couple of minutes and reboot.

If you want to go into hboot and look it should say s=off!

If you still have problems getting au to work after this uninstall visionary, shutdown, pull battery, and restart. Should work after that. Props to PolishDude for figuring that one out.

As always, you can brick your device if you fail to root properly. That said, if you think you can mange to root without bricking, the rewards are well worth it.

[Source: XDA-Developers]