As you may or may not know, it is impossible as a regular user to change the icons to some of the application launchers in the kde4 panels.
Such is the case with ooo apps.
Although this is just a detail, it is strange that it be so.
In the case of ooo apps, one way to change the icon is to edit as root the .desktop file that corresponds to the app that you want and change the icon line.
In my case, I wanted to change the ooo-writer icon, so I did:
I insist: it's just a detail, but when you change your icon theme and ooo-writer stays with that crappy blue ancient icon, it sucks.