You dont say what software you used to make up the routes (e.g. Basecamp) . In any event it helps if your mate has the same software on his PC , as said above send the file by Email.
If say you calculated the route on Basecamp, simply EXPORT the route to one of your document files and then attach it to an email.
A couple of watchouts, for best results ensure the settings on your device (and your mates) are the same, e.g. Faster route, no avoidances enabled. Also those settings should match in your software (e.g. Basecamp) that you used to calculate the route. Finally are you both using the most up to date map versions ?. Cover this all off and you shouldnt find any variations in the sat nav instructions between your mate and yourself.
Hope this helps