I did this job a few years ago. It is fiddly, but the key is that you get the parts from a scrap yard car for only a few £. This means you get to carelessly rip the door panels etc off the scrapped car first, hence you learn how not to bugger your car when actually fitting the new handles.
The key is not to damage too many of the plastic gromits that attach on the end of the linking rods between your tinkering on the donor and recipient car. You need to be left with a full set. It's a patient job.