The Valterra Mini Rope Light you're referring too has been discontinued but yes you could cut it and splice it to a 12V power supply.
If you're just trying to add an LED light strip to replace your current LED lights, then I recommend just going with the LED Light Strip # DG52683.
This light strip is 16' long but can be cut every 3 LEDs, blue in color, and has an exposed end for you to be able to easily splice into your setup. view full answer...