ushould be able to tell when u remove the upper timing cover. an easier way to tell is to take off the timing cover as well as the cam gears and the black cover behind the cam gears and look to see if oil is leaking there.
well, if its the front main seal.. u'll have to take off the fan, upper timing cover, upper radiator hose.. might as well take out the radiator too. lower timing cover. pull the belt tensioner off. take off all of the gears and pulleys. pull off the whole aluminum timing piece itself and get to front main seal and scrape it off. there alittle bit more to that. consult the haynes manual too for alittle help along the way. its in no way an easy task with the engine still in the car. plus, if its not the front main, u could have just wasted a crap load of time.
kk, im off to bed here in a sec. hopefully others will chime in.