You can do that with something like this:

    pkgs.yourpackage.overrideAttrs { prev: {
       src = fetchurl {
          url = "...";
          sha256 = "...";
       };
    }}

Bit annoying that you have to specific the full URL instead of just the 'version' number, but it'll work.

With flakes you can just add a 'ref' or 'rev' to the URL:

    nix run "github:juser/software?ref=v0.4.1"

If you want to override a package dependency across 'override'.

What does that version mean? What compile flags was it compiled with, which compiler, etc?