Using MMX/SSE/Etc in VB.NET

Is there any way to use MMX, SSE, 3DNow, etc in VB.NET? It is my understanding that the compiler automatically uses these sorts of calls where it can, but that isn't going to be as efficient as doing it by hand. For example, without the SSE averaging function you'd probably use a loop. The compiler isn't going to convert your entire loop into a function call for averaging.

I've been searching google, but it seems to be something that other VB.NET programmers have never considered or at least don't care about.