combo - meaning do you need to replace your springs at the same time or do you have to remove the springs from the shocks in order to get the shocks changed - you will need a spring compressor. You can buy relatively cheap ones or most auto parts stores will rent them to you. It's easy to do - you just have to be careful because a coiled spring stores a lot of energy.
Beyond that, it's just loosening bolts and swapping parts. You will also want to take it in for an alignment once you are done.