I've used tweaked War Machine on tactical hex maps, repurposing SPI's Medieval Battles Quad, using both battlefields and counters.
War Machine is a strategic engine, so scale is off, so I futzed around a bit with casualty ratios to make to make it fit better for unit vs unit combat. I did borrow some things from FGU's Bushido, but I don't recall the details, I think it may have been casualty breakdown ratios.
The main thing was to allow reasonable maneuver and to localize areas of spell effects. It worked OK.