How to get list of TraceSource's or retrieve a TraceSource by name?

Question

I would like to change some trace settings dynamically in code.

But I get stopped at the first step: How do I get an existing TraceSource object? Is there a way to retrieve a TraceSource by name? Or to get a list of all the existing TraceSource's? Looking at the docs, I don't see any collection.

Looking for a VB answer. Happy to get one in another language as long as it doesn't use constructs peculiar to that language.