Root my EVO wihtout USB cord
You can always put the files on an SD card and transfer them to your internal storage from there, but as was said in the comments, if something happens during the process and you are unable to boot your phone, the only way to recover from that is to reflash it from the computer, using the usb cable. You can use Titanium Backup to back all of your apps up onto the SD card, and hopefully you keep everything you can backed up through Google, but you still would have an unusable phone if something happened.