The front panel connector is a standard SSI compliant 24-pin connector. Pin definitions are documented in board TPS. Normally you'll need to connect the following pins:
Power LED ( 3-Pin Connector): 1-5
Power Switch (2-Pin Connector): 11-13
Reset Switch (2-Pin Connector): 15-17
HDD LED (2-Pin Connector): 7-9
To power on the system, you can simply short pins 11-13 with a screw driver.