NuMaps Lifetime and 60CSx

Has anyone successfully used the Numaps Lifetime process to update the maps
on a 60CSx?
Garmin's site shows the 60CSx as a compatible product, but my local supplier
says it won't work.
I've got a 60CSx with City Navigator NT North America on it (don't know
what version, but it's about 2-3 years old now)

Any suggestions would be appreciated.

Thanks.