Tax help for STP

STP, one more question about 1040.

I didn't take the retirement savings credit for last year joint return,

(1)I want to redo it with this year's return.Can I just put the number I overpaid for 2004 on line 65?

(2)If yes, which form I need to attach with it for document supporting, 1040(2004), 1040X, because I use 1040EZ last year.

(3)or I need to redo it separately using 1040X and mail it later? Many Thanks.