A 2610 would be severe overkill for anywhere out there.....it may be the king of GPS's in Europe but it's the mapping info that will le tyou down outside of the normal countries.
All you'll need it something that can take you on a base map, and maybe from point to point....older and cheaper units will do the job well.
Horizons Unlimied will be the best place to start a search for routes I'd think.....and many people there will have done the roue so a few polite questions should get you a lot of info.
To plot coords in places like that, if you can find a decent set of maps you can convert grid references to GPS coordinates....you'll have to do a bit of work though as many maps use different sets of dtum to set their positions....these are pretty well supported in Mapsource though, it's just a matter of changing the datum type to the correct one.
There are Russian militery maps in great detail for all sorts of odd countries if Michelin or someone similar doesn't do a set.....We looked at the maps that some mad Lithuanians had for the western sahara crossing route and the Russion maps were by far the best and most detailed of any available.
I'm still trying to find a set for this year's trip for the western sahara route.
