How Can I Set Hight Detail Jerseys To Low Detalis Jerseys

I try to use the editor jersey but I don´t know How.
Y try to add _lo to iff files but didn´t work
Any solution?

Just change player detail to high with the in-game detail settings. If the frame-rate drops too low when doing that it is because you don't have a dual core cpu processor and hacking high detail jerseys on to the low detail jerseys will do the same thing as the in-game setting.