However, whereas using LISP=ccl as the driver correctly invokes buildi.exe, using LISP=allegro as the driver leads to alisp.exe being called, which is not what I wanted. I haven't investigated why.
That was because defining LISP=allegro resulted in exporting ALLEGRO= which wasn't defined with LISP=ccl, and that ALLEGRO overrides the mechanism that in lisp-invocation calls buildi.exe instead of alisp.exe.
If you (Kevin, or any Allegro/Windows user) considers that it's a bug worth fixing rather than a feature, please propose an API as to how lisp-invocation should detect the correct way to invoke alisp.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org "Ask not what the government can do for you. Ask what the government is doing to you." — David Friedman, "The Machinery of Freedom", p. 21