Note that for plugin updates you will need to download aforementioned source from our repository, compile, and install just the shared object files over your 1.5.1 installation.
Specific compilation instructions and dependency information can be found on our Git page.
The Wadseeker 2.2.3 source is also included within the Doomseeker source download.
If you are looking for an older release of Doomseeker then you can browse the files directory listing.