Embed images in extension

I’m writing an extension (actually just a macro, but I plan on distributing it as an extension) that inserts images in a text document based on user input.

For now I retrieve the images from a predefined network location. But that location may change, and I’d like the extension to be usable offline.

So, I’d like to distribute the images alongside the extension, in the same package. My questions are :
1- how do I embed images in the extension package?
2- how do I access these images from inside a macro?