Yeah You can put them in the game.
First You have to save target as.... Then with eagraph open xplrmn.viv (not sure about this) if it's right you will see a file shoes.o or shoes.fsh
When you've opened that one, you will see al the shoes that you have at this point in the game. Use the left mousebutton to select the shoe you don't like and then import the saved shoe from steve's shoestore. This will replace the shoe you didn't like with the new one. It will automaticaly replace the old shoe with the new shoe at all the players that wore the old shoe in the game.
Ex.
T-mac wears his number 2's in the game, Look them up replace them with t-macs 3 and in the game they will be replaced..
Easy as that
Greetz
Jeremy