The bushing hole in the slide is probed, CNC machine for concentricity, the pocket is machined for the guide plug, then a proprietary thread is made using a thread mill in a CNC machine. This is clocked so that the bushing almost times to the fitting pads.
If you can set this up and do it yourself, then sure we can sell you the bushing.
We make the assumption that setting this up will be way more time consuming and costly then us doing it.