Once you’ve compiled the NVC simulation tool, you can customise Emacs to have it as one of the standard list of compilers.
Add these lines to the “vhdl-compiler-alist” section of your Emacs config file:
("NVC" "nvc" "--std=1993 --work=\\1 -a" "make" "-f \\1" nil "nvc --init" "./" "work/" "Makefile" "modelsim"
("\*\* \\(Error\\|Warning\\):.*\n.*> \\(.*\\):\\([0-9]+\\)" 2 3 nil)
("" 0)
("WORK.\\1" "WORK.\\2-\\1" "WORK.\\2-\\1" "WORK.\\1" "WORK.\\1-body" upcase))