you need to get hold of an USB-OTG Cable and an USB-STICK.
Place any suitable ROM onto the Stick, plug it into the OTG Cable, plug it the into the Micro USB Slot of your HTC ONE.
Boot into Recovery, choose MOUNT and choose USB-OTG. Now Go back to INSTALL, choose USB-OTG as Source, and there should be the ROM you placed onto the Stick to choose.
After the ROM Has been flashed you might have to boot into the Bootloader to flash a Custom Recovery and the boot.img.
Excuse my English, it's been quit a while.