I don't think you can make a standalone mod for BS because it itself is a mod already. If you want to do that I think you'll need to make a regular HL mod, and copy the BS content you need into your mod. Apparently Valve doesn't care if you release copies of their files as long as they're only being used for non-commercial HL mods.
Hopefully you can just add the DLL files from BS and hook them up with your liblist.gam file. Otherwise if that doesn't work you'll have to add custom code for the BS entities, but you can probably just compile malortie's bshift branch:
https://github.com/malortie/halflife/tree/branch-malortie-bshift(Again I can't confirm that any of this will work, not many people try modding for Blue Shift because of these issues. I don't know if you'll need the regular BSP format or the BS one if you do this, so try both)