Your question is a little vague.

   - If you want to build existing packages from source xbps-src is the way 
   to go. For pointers on how to do that check the void-packages readme 
   <https://github.com/voidlinux/void-packages/blob/master/README.md>.
   - If you want to create your own packages take a look at the manual 
   <https://github.com/voidlinux/void-packages/blob/master/Manual.md> on 
   github.
   - To create packages for kernel modules you might want to take a look at 
   the existing DKMS-packages like broadcom-wl-dkms 
   <https://github.com/voidlinux/void-packages/tree/master/srcpkgs/broadcom-wl-dkms> 
   or zfs 
   <https://github.com/voidlinux/void-packages/tree/master/srcpkgs/zfs>.
   
I sincerely doubt that you will have to recompile the entire system though 
:)