I recently went through all this, but I replaced my rag disk with a nolathane item from an Isuzu Gemini (Holden in Oz).
You can get the whole steering coupling out without undoing the rack, providing of course that the joints have not welded themselves in, but putting it in may be different.
With mine I replaced the rivets with bolts, but the nolathane disk was thinner then the rag disk so I had to space it out with wishers to the right “length” to get it all to fit. I ended up loosening off the rack so it would move a little then put the coupling back in. After a few trial and error fittings to get the coupling length right I tightened up the rack again and good as gold.
So, to sum up.
- You may be able to do it without undoing the rack if using a factory replacement disk.
- You may have to loosen the mounting bolts on the rack to get it all back in.
- Be prepared for 1.5 to 2 hours (out to in) if the couplings decide not to play the game.
It is all well achievable by the home mechanic and does not need specialist tools.

PM me if you want more detailed info.
Good luck
Cristian