I've never done that in the car, but I've done a few with the engine out. I understand it is probably cramped in there. My advice, remove everything that gets in your way to clear access. Lots of rookie mechanics like to try and dive right in to the problem, and end up spending lots of time contorting around something that would have been easily removed. Remove whatever you need to get good clear access.
You did replace the o-rings right? Do not try to reuse and goop them up.
Make sure everything is clean, and lubed, use some lube to make it slide in easier. I've even used simple green before. I typically put the connector piece in the block, then the water pump on it. Do not try to just replace the pump and leave the connector in place. It should come out, have the surfaces cleaned and then o rings replaced. Clean both the block and water pump surfaces good with a scotch brite pad and simple green. You don't want any crud hanging up that o-ring as it slides in.
Last edited by Tboy; 09-14-2014 at 07:02 PM.