[council] Senegal - Letter with State Dept stamp for personal computers etc.?

Greetings! Have any of the other US folks been told that, in order to avoid paying duty on personal computer, iPad, etc., one has to have a letter that itemizes the equipment, states it's for personal use, and bears a State Department stamp? When I asked if the State Department stamp meant apostille, the person at the Senegalese Embassy didn't know. Before I go (or, more accurately, my assistant goes) chasing this down to find out exactly what is needed, I thought I'd check to see if someone else has. Anyone? K