Replace the "inner" parking light plug with an identical plug as the outer ones (three leads I think), then wire them up in parallel to the existing one. I used a relay to operate all the bulbs, just as to not put any extra strain on the existing wiring. They worked great. You have your parking lights as usual, and then have "inner" turn signal lights flashing in unison with the "outer" turn signals.
On the rears, I rewired the back up lights to become tail/brake/turn signal lights and used a red bulb just so the Alabama non-driving fools would maybe actually notice that I was turning!!!
97 Lincoln Mark VIII LSC (Chip'd, 3.73 T/L... so far... )
97 Ford Aspire (Slow, but getting 36 mpg (f'n Ethenol!! )
84 F250 Dually w/6.9L Diesel (7.3L IDI pending)
73 Mercury Cougar Convertible w/351C 4V (Partially Restored)
69 F100 LWB w/460 Engine
76 Glastron Carlson 23' Jet Boat w/460 CJ Engine