WebGL Plugin. Customize emscripten linker

Hi. I have a plugin library I need to call in my App, but shipped to me as a llvm bitcode lib (can't get the source because IP restrictions) How can I link that with my plugin in Unity? Using emscripten and a self made project I can link this lib with my cross-compiled C++ code without problems so I think that I can do the same with Unity3d. In other words how to customizer emscripten linker libraries?

Any ideas?

Thanks!