Here's how I did it (version 3.0 of the mac client)
Open up SETI@Home Control Panel in ResEdit. MAKE A BACKUP FIRST!
Open one of the icon resources (icl4,icl8 etc. doesn't matter which one)
These are the icons you change:
-16493 (red flashing menu bar icon)
-16492 (green flashing menu bar icon)
129 (Icon shown at bottom of screen on Startup)
For the first two (the menu bar icons), erase all the pictures in the eight boxes.
This will leave a blank space in the menu bar where the little SETI icon is.
If you click where the icon SHOULD be, the little menu will still come up like normal. If you want, you can also change the names of the items in the menu to hide SETI even more from prying eyes

. Do this by editing the MENU resource.
Changing icon resource #129:
To hide the SETI icon at startup (on the bottom of the screen). I changed this icon to something
totally inconspicuous: the InputSprocket Extension icon. Looks perfectly normal.
To do this, open the InputSprocket extension (or whatever icon you want to change it to) in resedit. Open up one of the icon resources and copy and paste all of them into the corresponding little box of icon resource 129 of the SETI control panel.
Save all changes and quit resedit.
To see the changes (or not see in this case), restart with the modified SETI control panel in the control panels folder.
MAKE SURE YOU KEEP A BACKUP. Just in case
[This message has been edited by DocWest (edited 10-08-2000).]