Source:mirv_loadlibrary - advancedfx/advancedfx GitHub Wiki
Lets you load external .dll files.
All Source engine-based games that HLAE also supports.
mirv_loadlibrary <full-path>
Don't forget quotation marks if the path has spaces in it.
The full path doesn't need to be specified if the .dll file is in the same folder as the game .exe.