Fuel pump rubber insert into cup in tank! Help!

I have done a search and no one has any info to help me! Is there any pointers that anyone can give me to help me get the rubber insert into the "cup" on the bottom of the tank. I have a book that shows a picture and I have felt it with my hand- I just cant get it lined up right???
Does the tabs on the pump housing need to line up with the tab holes on the tank?
Do I just need to to turn it a little one way or anouther?
Looks like its best to drop the tank, so I am going to do that now and then I will check back to seed if anyone has some pointers!
Thanks