Scratch

When you install these tools, they generally propose to associate them to a number of archive types they know (zip, tar, gz, bz2, 7z, rar, etc.).
You can also do that later (eg. in 7-Zip: menu Tools > Options > System tab).
Moreover, you can right-click on any unknown file (say .xpi or .docx) and choose 7-Zip > Open in the context menu. If that's not a known archive, it just warns about that.