I bought cable lights for my bedroom. Can I alter the length of the cable rod that is attached to the halogen fixture without damaging the fixture?

Flickit

...propose to alter the length? Shorten or lengthen it? Either way should be OK but I'm not sure how one goes about lengthening it without a suitable kit. Shortening should pose no problem so long as the cut is crisp and clean. Don't want to weaken the cable or otherwise affect its connection integrity to the lamps. Check with the supplier if no clear instructions on cutting/shearing came with the assembly on what tool best cuts the rod.