The panels come off easily. One side has a push pin, the other a slot. Grab the back of the sidepanel--the side nearest the tail of the bike. Pull that end straight out. Slide the entire panel forward and it will come off.
The interesting part is I compared the side panels from my F4 and Brutale, and they differ in length. It's not obvious unless you put them side-by-side. So, I would compare the new and old pieces before you try putting the new one on. If the new one is made for an F4 it may not pop into place.
Can you link the e-bay auction? Do they have more?