It will depend on the gui you are using. If you happen to use the chessbase/fritz gui, press s to setup positions or if you want to play out the moves, click on the ENGINE tab, there you can switch off the engine and play both sides.
If you use another gui I can't help you.
Rybka 4, a question about a simple function
Oh lol, ofcourse, I even use that myself - duh -
If you want to just put in complete games and analyze specific positions the engine method is perfect, but if you want to evaluate every position, might as well have it running when you go through the game. (i use a laptop, so when I can I turn off the engine, to reduce heat)
Every chess program has a simple option sometimes called Create your own game where you move pieces on both sides. I want to Rybka to analyze games that are in the book I'm reading but I don't know how to transfer moves. Help me please :)