how do you change 904 front pump seal??

May sound like a stupid question, but its not because I dont know how lol. Anyway, I have a late 70's 904 trans. I believe it has lock-up on it- smooth on end of shaft instead of splined. Came from a 78-79 360 Cordoba. Im looking at the front seal area and I am guessing that you have to take the front pump off to change this seal-am I right? Will I lose a ton of fluid everywhere? Any tips? I will be searching through the archives more-havent found what I am looking for yet, but please help here if you know how. Trans is laying on ground under car as we speak. Any other tips, tricks, or should do's while its out? Is there a pump seal that would need replaced for around the bolt holes for the pump also?? Or just undo and replace pump seal by shaft?