First, let me just say, this was a nasty set to work with, due to non-standard placement (unlike walls and roofs). I did as many supports as I could before burn out, and not every single coaster was tested with each support, so you may have to tinker with the various styles to see what worx! I tried to align supports the best I could, but there are many variables involved with the different coaster types, so don't expect to cover every inch of track with a perfect fit.

I may do a small update in weeks to come which may add a few more supports to the mix.

You can download either the Automatic Installer, or the Zip file.

Automatic Installer (EXE). Download the Pumper-SteelWorx.exe file. Click on its icon, and you will be presented with an install screen, which will automatically install SteelWorx to the proper directory: Just click "Unzip", and it will add the folder to the proper directory on your C DRIVE. If you have RollerCoaster Tycoon 3 on a different Hard Drive, then make sure you change the "C" to the Drive letter where your RCT3 Game is installed.
** This is based on the directory structure for the US version
JCat's SteelWorx Automatic Installer 509KB

Manual Install (Zip)

If you're having problems with the installer, you can download the zip file, unzip it anywhere on your hard drive (which will be temporary), then drag the entire folder to the following directory:
C:\Program Files\Atari\RollerCoaster TycoonŽ 3\Style\Themed
JCat's SteelWorx Zip File 479KB
 

 
Support Killer

You can turn normally turn off ALL supports in RCT3, but if you have a large park of coasters, you may not want to have custom supports on every last one of them. SteelWorx does not support wood-style coasters, so it's best to leave your supports turned on and use the Support Killer (yes, it's invisible) to stamp out the standard RCT3 supports.
Tip: Turn on the grid overlay. Now, select your support killer and plant a large section of them on to the landscape, say a 10 x 10 square. Since these are invisible, you best remember exactly where you placed them. After you decide the size, select the scenery saver, and cover the entire area of the invisible grid with the saver selection tool. Save it with your scenery, load it back in, and now you can knock out large clusters of supports, instead of one at a time (no watching them bounce around before they disappear).

Tube Fat Extended
I know you're probably wondering what's the point of this when there is already a Fat Capped Tube. The standard Fat capped tube will not always line up correctly with certain coaster track heights. The extended tube is an alternate height (non-standard) which should take care of this. It's just a bit higher then the normal fat tube.
Small Track Support
These coaster styles were so different in height then all the rest of the steel coasters; not a lot was done for this  style (at least for the current release). When using these smaller tubes, be sure to keep hitting the Z key and you will notice the tube should align with "most" of those  RCT# support track pieces that you can't remove.
Horizontal Tube Pieces
Very useful for making vertical connections of course, but as a reminder, don't forget to hit that ol' Z key, because these will jump a space and not connect if you don't. For example, to make one complete connection, you'd place your first piece, rotate it hitting Z twice, place the second piece, hit Z twice again, add your third piece, and so on. 

The Strata supports are actually easy to use. The below sample is NOT the Strata Coaster sample included in RCT3. I redid the downward spiral to match the direction which the Top Thrill Dragster rotates, and which is how the Twist Support will fit (begins spiraling right).  The little bars holding up each platform is a Horizontal Tube Piece at each end. I will add more Strata pieces to the next update.

Strata Sample

Beam Sample


Above is sample of the possibilities which can be achieved with the single beams and Beam-X parts.