From AvSim I down loaded Garmin 530 and 430 FS Garmin.zip in 2004.  Freeware and nicely adapted by Don Kuhn.
Instructions need some minor clarification. 
Got both installed and running.  Not significant improvement over the original but may be of interest to some.
I need some help on gauge installation.  By gauge I mean the GPS Icon on the instrument panel.  The toggle doesn't appear but the virtual activation button is present.  I can tell because of the mouse pointer action and the GPS activates when clicked.  I know where the area is on the panel because of the x,y coordinates I placed in the a/c Main Panel gauge listing.

Errata for those interested:
2. "new FS9Garman.zip" should read "new FS9Garmin.cab."
4c. Problem is in "guage39 and 40=FS9Garmin..."  I numbered sequentially so not a problem.  I traced both files and they look to be correct.  Still no button.  I inserted FS9 button and comes up on panel except is the 500 Garmin.
4d. [window 06 and 07] "guage00=pGarmin!GNS530 and 430..." should read "guage00=FS9Garmin!GNS530...".  Unless someone knows that p = wildcard.
I also included "size_mm=500,366" as defined each window as the third and fourth values.  Mine reads for 530: gauge00=FS9Garmin!GNS530,    0,0,500,366
Don't know if required but I added.
Last and critical: These GPS must be turned on.  They don't appear on when selected like the 500.  On/Off left side of panel. Just look close.  Caused much messing around till I discovered why the Garmin but no GPS.

Resolution of Garmin 530:

Install edits as described earlier.

Button does not show on instrument panel.
I referenced from known panel button for location.
When mouse is over or near 530, pointer turns to hand.

Turn on.

Buttons for Garmin 530 selection differ from 500.

500 button top to bottom is Cursor On/Off; Change Pages within Page Groups; Change Page Groups/Move Cursor.  The knob arrows are location reference.

530 is top button Cursor On/Off; Change Pages within Page Group 8 o'clock and 5 o'clock outer ring; Change Page Groups/Move Cursor 11 o'clock and 1 o'clock outer ring.  Location reference by function pop up.

530 has VOR and COMM selection option.  Otherwise I don't see an advantage.