v1777 you would have to put the plugin files in the main folder and edit the plugins.xml accordingly. Most plugins come with a txt/pdf explaing the "magic line" edit
No clue what works with that version
Here are some rtl-sdr dot ru plugings from the last time the site was up for the community downloads
mega.nz
A member here also maintains & updates some plugins for sdrsharp
24 files and 17 subfolders
mega.nz