When I built my truck I got extremely lucky. Gumby had just started on building his Sema XR and was getting rid of all the body kit and suspension/chassis parts that were specific for the XR. The only thing I didn't have other than the 4.0/6sp was the front struts. Everything else was how a single cab X would have been from Toyota. I had all the X braces and the rear sway bar and rear bilstiens. The front sway bar is the same on the regular 5lug tacomas as it is on the XR. I was quoted over $5400 for all the body kit and fasteners from the dealer. That wasn't including any of the suspension or chassis parts. I bought everything from Gumby for $1,200. :rock:
As far as modding the side skirts goes, it is really pretty easy to do. I cut 17 3/4 inches right out of the middle in between the buldges. There is just enough room to cut the skirt without cutting into the buldges. You also cut the mounting hardware in the middle so mounting points on the skirts still line up. All the mounting points lined up with the holes and captured nuts on the bottom of the reg cab. It is kind of hard to describe.
visracing.com sells a fiberglass reproduction of the XR kit for the reg cabs.
http://www.visracing.com/oldcatalog/index.php?cPath=26_31_444 . They show a pic of the X-Runner but the kit is for the reg cab. Probably be a lot more cost effective to just buy their kit than trying to build it with Toyota parts. Unless you get lucky and find a XR in a scrap yard that has everything intact.
As for the suspension parts I would definitely reccommend getting the XR stuff. It makes a huge difference compared to the reg 5lug tacoma in the way it handles and rides.