Because the Slatwall panels are vinyl, you can cut them with a normal power tool, or even with a handsaw. No matter which type of saw blade you want, use a fine-tooth blade for clean cuts across your slatwall panels. If you want to go one step further, you can cut the pre-made wooden slatwall panels to specific lengths with either a handsaw or circular saw, or you can add extensions to make them longer if your ceiling is tall.
Decide the width and grain of the wood slat wall panels that you would like to use. This guide will produce enough slats to cover 8 feet of wall- plan on adding additional wood and supplies if needed to cover the area you are working in. If your slats are too wide to cover your walls, you can always trim them. If you would like your slats to hug your wall tightly, you will want to use nominal 1/2″ plywood (about 3/8″ thick). The plywood is 3/4 thickness, so as soon as you lay your slats down to use them as a spacer, this will be the spacing between your boards against the wall.
Now that you know the first slat is flat, you can put away your measuring tools and just use the extra piece of wood turned on its side as a spacer between your boards for the rest of your DIY stainboard walls. If you are building your garage slatwall using 1x, then use the scraps as your spacers when installing horizontal slats. Use smaller pieces of 1-x2s as spacers between the 1-x2s that you are affixing to the walls, so that there is consistently equal spacing between boards. Cut the 1x2s to the right dimensions, then use a combination of panel adhesive and nails to attach them to the wall.
From there, it is really just pre-drilling holes, then using black screws to drill the felt into the wall.
Once your supports are dry, you can move on from staining the boards and begin building the walls. If you are worried once your garage slatwall is built that the drywall behind may be ruined and beaten from constant use, you will want to install either stop screws to prevent the installation of any of your slatwall accessories, or install a luan sheet of wood (ref) that will prevent any things from hitting the rear wall behind your slatwall. Painting before installing your garage slatwall will let you use a roller on the whole slatwall instead of having to paint it manually, in order to achieve a recessed finish.
After you hang it up against the wall. There you have it, three options at three levels of budget that can help you build the wooden slatted wall feature you are looking for.