I am splitting this issue off from #1796, because the discussion there got long and so potentially also intimidating. I think this is a very important feature that will be great for intero and similar tools. The idea is simple:

stack install --compiler-specific will be a magical incantation that installs tools directly to the compiler bin directory. It is easy to implement, and an important enhancement, so I am marking this P1.

For global installs of GHC, it should warn that it might not have the intended semantics. Like if ghc is in /usr/local/bin, we may well be overwriting intero compiled against a different ghc, and that might not be expected.