I'm planning two mountain/big hill trips before the end of October and have being using the OSI (Ordnance Survey Ireland) Map Viewer to get a better idea of the routes to take. Each of these involves a cache or two (natch

It's years since I did any sort of map work and I may have to do some revision but ..
Is there a way to convert the OSI X/Y references to GPS data, e.g. N 53 NN.NNN W 06 NN.NNN ? I assume that the OSI map data is local to Ireland so if there were a method for converting one to the other, it would have been developed locally.
For example, could I take the GPS co-ordinates off a cache listing and convert them to an 'OSI' equivalent ?
Thanks
PS I know I could probably achieve the same outcome by RTFMing my GPSr manual
