jdh2550,
Yes, you can cut them with dremmel, hacksaw, etc... Just were eye protection, gloves, and a mask because the carbon fibers are nasty(think fiberglass). You can cut the sleeve 2 or so inches shorter than the liner(to leave room to reinstall the last muzzle end shroud spacer on the liner)
These carbon fiber sleeves are made up of many idividual strands of carbon fibers. As such, they tend to come unravelled/frayed when you disturb them. So, before you cut, wrap the outside of the tube in masking tape where you are going to cut it. Also, put a wooden dowel(or steel rod, old FX liner, etc...) that is as close to the inside diameter of your carbon tube as possible inside the tube before you cut, to prevent the strands of carbon to unravel inwards while you are cutting. Then sand/buff/clean cut the cut sleeve and install on your liner.
Good luck