Best posts made by Jackal

Try [c]M98 P/macros/test[/c]

@theruleslawyer Some slicer allow you to set a minimum layer time so that it will slow down the print, there may also be an option to set a percentage of minimum printing speed on top of that since a very slow print may lead to the hotend staying too long at a spot.

http://reprap.org/wiki/G-code#M581:_Configure_external_trigger
You can try using this to set up triggers and corresponding g-code to achieve what you need.