Unfreakingbelievable!!!
I just collected all the bits together to begin this job today (before the heavens opened up), I hunted around town for a semi decent Torx kit (why buy just one when the XJ needs an assortment) and located a Kinchrome Torx (tamper resistant) bit set mounted in 1/4 & 3/8 drive sockets at Bunnings Hardware for about $26.00, now even though they're mounted in a socket with a bit of a "tap" you can knock it out and use it as a simple Torx bit...
One thing I noticed was using it as a simple bit I was required to mate it to a 10mm ring spanner, I'm not confident this configuration will work without snapping the spanner so instead I had planned to jack up the right side of the engine (after removing the engine mount bolt) to create sufficient clearance to use a 3/8 drive ratchet (and maybe a pipe extension)
FWIW T60 is right on the money!