do you want to change the icon size in the kmenu as a user..?
if so - here's what i did:
open your user account /home/your username
choose 'show hidden files' from the view menu..
open .kde
open share
open config
open this file: kickerrc
almost at the bottom you will find [menus]
i changed to the value 16 in this line:
now i have same icon size as under root..
cheers :-)