Steering wheel on a '78B. Special tool?

[Tab Julius <tab@penworks.com>]

In trying to replace my turn signal/highbeam switch, it looks like a weird 
screwhead on the steering wheel cover.  Do I need a special tool?  If so, 
what?  Or can I get at it if I can find the perfect-sized 
screwdriver.  It's hard to see the screwhead, given the location, but it 
definitely doesn't fit anything I seem to own.

TIA,

- Tab