Seems like I remember a post sometime back that Butel included the preloads somewhere with their software. (But that may have been referring only to a specific ARC version.)
You can download Uniden's programming software,
BC246T_UASD, which will include the preloads along with the program. It's the demo version, not the full version, but that will get you the preloads. (You don't have to buy a software key to install it & generate the preloads; the key is only needed if you wanted to use the full version. )
I did not see them any longer on the 246 group (could have overlooked them). Zipped, the file is 28kb with all 65 preload systems. PM me your email if you want the zipped version.