Yes it should be possible to change the ignition barrel.
Anyway, we bought a full set of cylinders from Fiat for our Ritmo (Strada). It was delivered with ignition cylinder, two door cylinders and one cylinder for the hatch. We only changed the door cylinders. A little complicated until we understood how to do it - some pin out here, and one half turn there etc. So we have one key for the doors, and one for hatch and ignition. Works pretty well. You can let your car idle and still lock the doors. Can't think of any time that would be appropriate, but still...
To remove the lock on the doors, you must remove all interior from it. Then there are two nuts (size 10 I think) securing the handle to the door. No mechanics to worry about.
Morten.
gas lowered on abarth wheels. upgraded interior and visuals. audio through phoenix gold and BLOWN kenwood.
projects: air in and out.
Honey that ain't no pistol - that's my LOVE GUN.