my guess is you'd have to tear it all apart again to install the wiring harness. I'd go the DIY route myself and get them hooked up asap.
you may have a harness already (small chance I'm told) but you'll need some kind of switch. you might be able to get both a harness and switch from a junked gt. if not I know the factory switch can be purchased.
GT500 Front End Swap, Monster H1 Deep Draw Hood, Web Electric Sequential Tail Lights, Smoked Coyote Tail Lights, 2010 Interior Door Panals, 2012 Sun Visors w/ Illuminated Mirrors and Homelink