‘Xologist’, a senior member at xda forums has come up with the instructions to root your MyTouch 3G Slide smart phones. Actually he is not the only person to take whole credits of these steps as he has just compiled the information from various sources. He said that the reason for this compilation is that he is unable to find any real thread till now that actually contains full rooting information. So, he has made this one single thread so that it can prove useful for all and users are able to find all the steps at single page.
Rooting MyTouch 3G
1. Download zip file Esprimg from here
2. If you see that the above file that you downloaded is suffixed by numeric 2 then consider removing the numeric so that the file’s name is now ESPRIMG.zip
3. Put this ESPRIMG.zip file on your SD card’s root.
4. Switch off your smartphone.
5. Press and hold Power and Volume Down buttons at same time and Power-on your smartphone.
6. You will see that some loading is appearing on your mobile’s screen.
7. Wait till the loading screen disappears.
8. When the loading screen disappears, you will see that you are presented with some instructions.
9. Press Volume-Up so that Flash is confirmed.
10. Wait till the process is complete.
11. When the process completes, your mobile phone will be un-rooted with the stock Espresso.
The instructions poster guy has also stated that if you want to replace your smartphone and are sending it back to T-Mobile then consider flashing the newest radio file.