i dont know about xbox 1 but i assume its the same.. you have to extract the iso on your computer using xbox image browser and then put the extracted folder on the xbox harddrive and boot the default.xex (or default xbe if xbox1)
you need a flashed xBox (mine is flashed with the executor2 chip) and a different dashboard to MS - I use EvoX - as this dash will search all drives and when a game is found will display it in the main menu
only problem is the XBox only comes with a 10 GB HDD - around 8 GB can be used, so you are pushed to get 2 games on - I am going to install a 80 GB hard disk this weekend so I can copy more games one
I use this cos of the excellent XBMC and turns the XBox into an amazing media centre streaming directly from PC
how did you soft mod it.. I got a mate to solder the executor chip on to it in 2003 and never looked back.. would be interested to softmod another one as I am sure cna pick up a cheap xbox for 20 quid I guess.
I used the Splinter Cell method, no need for the action replay thing as I got a xbox to usb converter lead for a few quid from ebay and just used a usb memory stick instead.