It's a pretty easy install. I've had to change winch cables on the trail before and was successful.
The hardest part sometimes is being able to reach the spool, sometimes you have to take the winch off to get it started. Also, while you have the cable off put a stopper on if you don't have one already, if you do this make sure you pass it through your fairlead before spooling it.
For what it's worth I still use steel cable instead of synthetic rope. I ride in the mud and I worry about mud, dirt, grease, rocks, tree limbs and water ruining the synthetic rope. The biggest advantage of synthetic over steel is the breaks aren't as violent. To accommodate this I always put a sweatshirt, tree limbs or something on the cable while winching make everyone stand away from the winch and I operate the winch from remote when possible. I also replace the cable at the first sign of wear (usually 2 years, it depends on how much plowing I do for winter).