I must say that I'm not terribly familiar with Equus' product and what the requirements for hookup are, however, I would suggest contacting Speed-O-Meter Service, Co. They're a very knowledgeable company that we work with on a regular basis and refer many of our customers to for application specific solutions. I've provided a link to their website for your reference:
http://www.speedometersolutions.com/
Hope that helps!