That’s an old posting before liosha’s script was available
My solution to the routing across tiles problem is more of a hack, rather than a solution. I use osmosis to split my OSM data into tiles, and the connecting nodes of the splitted roads are manually tagged as “garmin:is_external_node=true” (they are currently not that many in OSM Malaysia). In liosha’s script I added a conditional statement that will change the nod values for these connecting nodes (see http://forum.openstreetmap.org/viewtopic.php?pid=13274#p13274)
My previous tests shows that it works when the tiles are square (the connecting nodes are all at tile borders). I’m not sure how it’ll work if the tiles are irregular as in the shape of a state or country. Had a plan to experiment on this but haven’t got started yet
It’d be great if osmosis or any tile splitter tool can automatically tag the connecting nodes as such, rather than doing a major overhaul of your current tools.