Pedestal Steering Brake
What you seem to be looking for is called a pedestal steering brake, and is available through West Marine, listed for $144.99 - see page 921 of their 2003 master catalog. Although it's expensive, it's cheaper but not as versatile as an auto pilot. You need to remove the binicale compass to install it.Most fin keel boats will NOT hold course with a wheel brake either under power or sail for more than a minute, but it may get you enough control to be able to go forward to reef or drop a jib, if single handing.