An Emacs configuration file to get you started can be found here.
VHDL-Tool's linting and syntax checking features are also accessible from within Emacs through the Flycheck plugin.
Copy as much as you like from the sample emacs config. You will need at least the VHDL-Tool flycheck checker definition.
Then, start the vhdl-tool server and then Emacs:
$ vhdl-tool server & $ emacs