well, "Click to Front" commodity works here. Note that double-click is needed to bring the windows to front.
If you want the same behaviour as in Windoze (single-click), then run MCPPrefs and edit these entries in Hotkeys section:
"Activate Window under MousePointer"
"Active Window to Front"
Change the middle-mouse button assignment of BOTH entries to left-mouse button (by pressing "Definition" and then first "Sample" button). Don't forget to SAVE your new settings ;) Note that you need to restart MCP in order to apply new settings (or simply reboot after save).