Can / how is this done? I've tried using Tyre, but without much success. I recently bought a 720 and would like to plan some motorcycle trips. Is it as simple as exporting the maps to a memory card? Thanks for the help.
Importing MAPS from Google - No you can't. That is impossible on any TomTom.
Importing locations or route details - that's possible.
On your model you can use .itn itinerary files, so you just need a utility to convert to that from the .kml or whatever you're getting from Google.
The "Houghi script" mentioned above still works too AFAIK.
I use Tyre with my Tom Tom and it works very well. You are not importing maps - you are planning your itinerary route with waypoints on Tyre and transferring those start, end, and waypoints to the Itinerary screen on the Tom Tom using Save to Tom Tom on Tyre. Check your route on the Tom Tom after you do this as it may recalculate the route to what it wants to take to and between those points.
I never got Houghi to work and TYRE to work quite well for ".itn"s.
In the days of unlimited POI distances I found it much better to make a custom category, make POIs in HOME then opened TYRE and moved the to the exact coordinates and renamed them to something meaningful (instead of TomTom's street address).
With Add Community Content in the MyTomTomSupportApplication (computer tray) Custom POIs can still be installed.