I recently replaced my head and gasket after cracking due to overheating due to a broken thermostat and incorrect temp gauge on my 2000 TJ 4.0. I was told that you could pull out the lifters without removing the head, but the hole where the pushrods go down to the lifters was too small so i had to wait till the head was off, so no. The easiest way to check is to just pull the valve cover and look, it has a reusable gasket so you can just put it right back on.
My question though is why are replacing the lifters? If its because they are tapping or you suspect they are worn then the bad news is you will also have to replace your crankshaft as well because the lobes are worn also and those two parts wear and break-in together and both therefore must be replaced together. Mine werent tapping but where concave which means I should've replaced them however i didnt want to go through the extra steps for the crankshaft and I want a stroker so... when it does go I get to get one.