Actually, I would love to play this conflict as I have been interested in Mexican History ever since I lived in Mexico City way back in the late 1990s (my wife also teaches Mexican History at the college/university level). Good rules to use include either be one of the Two Hour Wargame skirmish rules or maybe even Piquet (the ACW supplement). Foundry has figures for this period in 25mm (see http://wargamesfoundry.com/our-ranges/old-west). They would be a great range for a skirmish set of rules. Also Freikorps makes a decent line in 15mm (see http://quickreactionforce.co.uk/index.php?main_page=index&cPath=438_578). Until I get the time to play this period, I’ll just say Viva Mexico.
Happy Cinco de Mayo from El Granadero Loco