Sometimes command+return will work (or command+shift+return?) to switch to windowed mode, but this only works with some Wine games, not with others. If you've already got another mac-related keyboard shortcut set to this combination, you'll need to toggle it off in system preferences>keyboard>shortcuts.

If you hold down the "option" key while double clicking the game app it will bring up the Wine menu, where you can change resolutions/etc. under "Set Screen Options" but I have personally not had much luck with this method.

From the same Wine menu (under "Advanced") you can add flags to the .exe line, "-window" (without quotes) will sometimes work if it's supported by the particular game.

Unfortunately with Wine games if you can get to a Windowed mode the window is (often/always?) not a resizeable window. Also sometimes you can't move the mouse outside the window and still need to close the game if you want to do something else on your desktop.

(Sorry I cannot comment on Wiz8 directly, I have not got around to playing it yet!)