Looking at Metzelers website it lists the following TL marked Karoo 3's as suitable for the XT660 (mine is an R but I think they are the same rims as the Z), but the bike has a spoked wheel.

90/90 - 21 M/C 54R M&S TL
130/80 - 17 M/C 65R M&S TL

On my XT600 I only used Tubetype (TT) tyres.

Anyone fitted tubeless type tyres to their XT? Did you just fit tubes? Or did you need to seal the rims?