although i dont have my ps3 setup, as long as the jtag'd box isnt using the drive as an internal drive (i have one like this), and its just used as an external drive connected via usb, it should be fine.
if its not, reformatted to fat32 will allow you to play SOME games off of the external hdd... view compatibility chart either way.
ps; you could if you just want to connect to ps3 only, remove the internal drive and run a sata cable out of the slot, and connect external power to the drive and run the ps3 with the 1tb hdd