Is it possible to compile a VB6 class into a Linux shared object?

Question

I have a legacy app written in PHP which runs on Windows IIS. I want to move the app to a Linux server, but there is a dependency in the app which uses a class written in VB through ext-com_dotnet. The class exists as .dll and is registered in Windows.

It's used like this:

$thing = new COM('cls.className');
$result = $thing->doStuff();

I have the source code of the VB class, which has a .cls ending. Can I build/compile/convert/transform/* the class into a linux shared object (.so) file which I could include in my app as a custom php extension?

The class provides critial unique functionality for the app but has no dependencies itself and has only two public methods and a few internals.