A button (or the equivalent on your controller) to advance after selecting teams, then Edit Uniforms, then the back triggers/shoulder buttons to cycle through them.
You can go to each side, select the jerseys first by selecting the Edit Uniforms option, followed by putting your icon back to the middle so you are not controlling a team.
"I don't know if I practiced more than anybody, but I sure practiced enough. I still wonder if somebody - somewhere - was practicing more than me." - Larry Bird