if you are able to save the nuts, game on. just make sure that the threads are good and no meat from the threaded hole stayed with the nut threads. I think you should be able to loosen the nuts on the ABS unit without too much trouble, it's the ones on the under side of the truck where the hoses connect and the wheel cylinders / calipers are that I would worry about trying to save without rounding the head or the line being stuck rusted in them.
to keep the air intrusion at a minimum while installing the new lines. get you a gallon of brake fluid and keep the MC full at all times. it will slowly gravity feed while you have things open. get all the lines up and installed to the 4 wheels first and have the bleeders open. wait till you have them all setup and ready to swap over into the ABS box last. as you pull one line off the ABS box at a time. cutting the line and slipping the nut on the new line, flaring and installing. the fluid should just slowly seep out of the ABS box. when you connect the new lines, leaving the bleeders open at the wheels will allow the fluid to start flowing out and eventually you will have the air out while you work on each one.
tools you'll need is a brake line tubing bender for the sharp bends. and a medium can of beans to make the coiled wraps similar to how the factory lines are under the hood. also a double flare tool.
use anti-seize on each nut going in so the next guy working on it will thank you

and remember tighten them up but not over tight, since this is a softer more malleable than steel line over-tightening them can squash the flare and not seal well.
cleanup is easy, brake fluid dissolves with water. so wash it all down with the garden hose. if you get any fluid on the rear shoes, just use the garden hose sprayer on them and blow off with air.
Your gonna go through a lot of fluid bleeding them so keep that MC full and constantly check it throughout the whole process. once you get all four wheels working, then it's time to power bleed them to get the ABS working. after that, it's the fun part testing the ABS on a gravel patch