There's no way to have jetways without installing GSX, which is not used "just" for jetways, but also to create Docking System and Marshallers. GSX is obviously free to use there, so there's no reason not to install it.
I don't understand the reason of your unfunded "fear" of GSX.
Even if we supplied an alternative AFCAD with standard jetways, you won't achieve anything other than having a serious downgrade of the scenery, from proper SODE jetways to buggy and worse looking standard jetways, no docking systems, no marshallers and, you would STILL have to install ALL our support software (Addon Manager/Couatl) anyway, because it's used to enable the Trial AND verify your license so, considering the support software is mandatory, and the SAME software also runs GSX, it wouldn't make any sense to use it only for DRM, when it can be way more useful to you.
I'll try to explain it in a different way:
Since all our sceneries automatically install the support software anyway, but NOT the GSX objects/textures, we can keep their installation reasonably small. If we wanted to give you the illusion "GSX is not required", we could just add all the required objects from GSX ( jetways and their textures, docking systems, marshallers, etc. ) IN the installer, making it larger for no reason, because ALL our installer would become larger, just to include all the required objects which are now SHARED by GSX. I hope you would understand that, it's really absurd to have many installers 2-3 GB large, full of duplicate files, instead of 200-300MB as they are now JUST so you might think the scenery "doesn't require GSX". That would be highly inefficient, wasting bandwidth, download and install time when now, you only download and install GSX ONCE.