I set the options in Scid VS. PC 4.8, so that Tablebase information shows up in game information window (when 5 piece endgame is reached. But when I turn on an analysis engine, it still does not recognize the tablebases, and continues to calculate, showing score +3.0, while the position is mate in 31 moves (as shown in game information window). Is there anything else I need to do? I tried several engines, with same results.
I just had the same question, and I thought I would post a belated answer for future persons.
I am using SCID vs. PC, but I think the solution may be the same or similar. First download the Gaviota tablebases here (http://www.olympuschess.com/egtb/gaviota/). Then go to SCID --> Tools --> Analysis Engines and select your engine (Critter is working best for me here. I have Houdini 1.5 and it is not working properly.) click Edit and then click the Configure button. You will see a GaviotaTbPath textbox; enter your directory, click save and everything should work.