All you need to do is breakdown the valve train (5 min), remove the push rod tubes (15 min) and pull out the lifters with a magnet (2 min). It's very important not to mix lifters and bores so either remove one at a time or label them so you don't mix them up. This is because each lifter wears against the cam lobe which wears against the lifter on the other side. If you are thinking you can swap them left to right, you probably can but I don't see any benefit to doing so. The underside of the engine is a dirty place so keep the lifter 100% clean of debris and also clean the area near the bore before attempting to re-insert the lifter.
If the lifter has an oiling hole in the side, a wide waist and a lock ring on the end, it's almost assuredly a hydraulic lifter but the only way to be 100% sure it to take it apart. Because after-market lifters look a little different than the factory solid lifters, identification can sometimes also be difficult.
Information taken from here
http://www.ratwell.com/technical/HydraulicLifters.html" onclick="window.open(this.href);return false;