Is there a way of including lisp routines in ICAD menus (similar to the .mnl files in autoCAD)

You can customize menus and toolbars, to include the lisp routines, in Options > Customize.

If you want ICAD to load the lisp routines everytime it starts, you have to edit the ICAD.LSP file in the IntelliCAD installation folder and write the proper path.

Sorry, I made a mistake.

The correct menu is Tools > Customize...

You'll find the Import button. You can import or export .mnl files.

You can add more menu items in the menu via the buttons at the center of the box.

In the ICAD.LSP file you'll find this line:

(load "dline")

just copy and paste it and change "dline" with the proper path and file name as many items you need.