Just edit the svg file in (by default, mine is different 
)
c:\Users\Owner\My Documents\Fritzing\parts\svg\user\breadboard
..\icon, ..\pcb and ..\pcb
which is where Fritzing puts the svg files. The fpz is in
c:\Users\Owner\My Documents\Fritzing\parts\user
(where Owner is replaced by your Windows user name)
These are hidden directories so you have to set in explorer:
explorer->Organize->Folder and search options->view->Show hidden files,folders, and drives.
which is disabled by default. I just leave it on always.
Peter Van Epp