Actually, you can, technically...
LATITUDE/LONGITUDE:
* Four(4) numeric digits followed by an optional North(N) South(S) clarification
* A forward slash
* Four(4) to Five(5) numeric digits followed by an optional East(E) West(W) clarification
A valid Latitude must have degrees between 0 and 90 and minutes between 0 and 60.
A valid Longitude must have degrees between 0 and 180 and minutes between 0 and 60.
LATITUDE/LONGITUDE
* 3857/07727
* 3357/11824
When we file flight plans, especially for the rotarys (I just had a 22 today that did it) they will sometimes terminate a leg inside of a Restricted area. When this happens, they will either give us a radial or a lat / long destination / departure point. These are valid for VFR routes, but not for IFR routes...
Now as to if FS will allow you to do this, that I don't know...you could possibly use the GPS and plug in cords, but I'm not sure..haven't gone that in-depth with the GPS yet. If you are trying to get to a specific point, say fly over your house, land at it etc...the best bet would be to just enter that in directly in the "GO TO" and just fly to the rough location from there.