I’m sorry, but I don’t think it will be possible to display the maps inside the infinite scroll area.
Because the Google Maps API is large, MapPress only outputs its scripts and map data (POIs, styles, etc.) when a map shortcode is present in the current post. They are output in the blog footer, during the wp_footer() function call.
My guess is the scroller is fetching the post content for each page, but not the footer. That makes sense for the scroller – but in this case the footer would normally contain the map scripts and data. Without them, it won’t be possible to just call an ‘initialize’ function and draw the map.