I am not sure if you have the Yacht Specialties binnacle and steering gear or the Edson brand. Edson is still in business and sells the cable repair kit. It is very important to make sure that you have the same cable ends for either brand as they have narrow clearances, but I think a rigger could make a new one for you from the old one. I am sure there is a Youtube video on the process of removing and reinstalling the system. It is not difficult, but requires some patience and care. I would be interested in what is leading you to replace them.
Generally, with the binnacle open at the top, you remove the cable bolts on the quadrant. Attach messenger lines to each and pull the chain and attached cables straight up and out. Once out, you put the new cables in place and reverse the process with the messenger lines. The cables and turning blocks should be lubricated periodically and tightened. Not bar tight but snugs so there is no play in the wheel to rudder connection. FWIW. If maintained, cables will last a long time. While you havef the whole thing apart, consider servicing the wheel brake. This brake will save your steering system from moving and wear when on a mooring or at anchor.