Ok this is just from memory so here goes.
Go underneath the car where the front part of the handbrake cable connects to the rear part which is under the drivers side. There is no need to jack up the car unless its lowered. Put bricks behind the wheels so it doesnt roll back.
Right at the end of the cable remove the circlip which secures a 'pin' which holds a bracket which connects the cable to an 'arm'. There should be another circlip a little futher down the cable and remove that also. Push the cable through the chassis rail. Reach to where the cable goes through the firewall into the cabin, its right next the exhaust so make sure the car is cold first, there should be 4 nuts (10 or 12mm I think) which secures a small cover/plate type thing. You dont have to unbolt them completly, just loosen them off as much as you can.
Now into the car.
There should 3 nuts that hold the handbrake lever to the car. 2 on the firewall and one that connect to the underside of the dash. The bolts on the firewall are above the foot rest, the other one should be pretty obvious.
The complete cable and handbrake handle/lever are now ready to be pulled from the car.
Once its free of the car, now its time to remove the cable from the lever. There should be a circlip at the end of the lever(firewall end of it), remove that. Remove the pully which is held on with a circlip also. Now its either fully extend the lever or fully release, I cant remember, and it may take a bit of effort as you said the cable is frayed. But right at the end of the cable there will be a ball type thing, line that up with a ‘hole’ in the lever, and unhook the end of the cable from the lever. Cable and lever should now be separated!
Line up old cable and new one to make sure they are the same.
Now for the installation :)
Now I tried threading the new cable through the firewall from the cabin side but I couldn’t do it, so I threaded it through underneath the car.
Now with the end of the cable sticking through into the cabin, making sure its in the exact same position though the firewall as the old one, connect it to the handbrake lever, first with the end of the cable, then connect the pully and then the hard part, the ciclip which holds the handbrake lever to the cable.
Bolt the 3 nuts back on.
Now the underneath of the car should be pretty straight forward, but getting the cable to thread through the hole in the chassis rail is not easy, and re-clipping the circlip.
Once that’s done reconnect the end of the cable back to the bracket, and then retighten the small 4 nuts for the cover on the firewall.
Now get in car and pull the handbrake lever and everything should be back to normal :)
If youve got any more questions dont hesitate to ask.