There’s a function called get_open_link() in ‘mappress_poi.php’ that does something similar.
<a href='#' onclick='mapp0.getPoi(0).open(true); return false;'>Click me!</a>
‘mapp0’ means the first map on the page, you can also use the “name” parameter of the shortcode to assign a different name. getPoi(0) means get the first POI, getPoi(1) is the 2nd, and so on. And .open(true) means open and zoom in – set to false to just open the marker.