My mechanic was mentioning that my CV boots need to be replaced since they're old and worn. I searched but I couldn't really find anything on the difficulty level or step by step on how to do it. Thanks.

You have to pull the half shafts and take the CV's off. You really need a press to do it as there's a spring washer you've got to compress to get the snap rings on

I wouldn't do the job without fully servicing the CV's. Clean, inspect, replace CV if necessary, all new boots, new grease and replace. Unless the boots are new-ish or perfect with no cracking I'd replace them all.
It's a real crappy job so you want to do it right the first time.

Here's one thread
Here's many more.