Original tutorial HERE
There are plenty of Softmod tutorials out there and all of them are good but getting the save files onto the Xbox HDD is a pain, I made a live cd that makes it easy to do just that. This is not a complete softmod tutorial, this is just to get the exploit files onto your Xbox to start the process.
First you need to buy or build a USB to Xbox adapter like this
Next you need to download my LIVE CD here
Burn the ISO to a CD-R with imgburn or to USB with Rufus https://rufus.akeo.ie/ (I tested this)
Boot CD-ROM or USB stick in any PC (please test)
Once booted you should see the desktop, first open the action replay shortcut
then open the action replay folder
then open the action replay app
If your controller is plugged into the PC and your MU is inserted into the controller you should see a green AR symbol at the top of the window
Next open the softmod folder
next select the game save folder you are using to softmod, in this example we are using Mech Assault
Next drag and drop udata.zip to the memory card pane
Now you should see the yellow progress bar start to move above the memory card pane
Once you see your save in the left Memory Card window, you are all set! Now insert your MU back into your XBOX and copy the save file over to the hard drive, then continue your softmod by running the save game from inside the game of your choosing.