If you don't want to compile it yourself, the blog post has links to binaries. Since they're entirely self-contained, you don't need a full .deb to compile them; just delete the binary when you want to get rid of it.
It works. The binary is 11 MB, or 1.5 MB stripped. ag is 69176 bytes. Shared libraries were a good invention :-) Sooner or later rg will be packaged properly too.
