Dave S wrote:
I believe there is an AC that
deals with IFR GPS useage that provides one means of compliance.

Ok, did some of my own searching, since at some point in the future I
will be retrofitting an IFR gps into a kitplane...

And I am unable to locate a current AC or TSO that REQUIRES the
placement of an annunciator in the scan like I previously mentioned.

AC 20-138, which is no longer valid, mentioned text that supported my claim.

The KLN 89 series pilot's guide, however, REQUIRES the use of a remote
annunciator in IFR approved installations. So somewhere along the way,
the manufacturer was told "thou shalt do this" and they incorporated it
into their "requirements" and I am reasonably sure that any flight
manual supplement issued by King for this device will indicate that
their remote switches and annunciator are required for IFR certification.

http://www.windsorflyingclub.com/documents/kln89b.pdf
Page 22 and 23 appear to have the defining text and graphics.

If you are installing this in a certified airframe, my recommendation is
to discuss this issue with the avionics shop that is doing the install.
In recommending that, I am recommending that an avionics shop DO or at
least supervise the install. Go someplace that deals in the equipment
and has done several of that piece of equipment in your type of airframe.

Dave