From Bordeaux :

A63 motorway towards Spain.
Exit Bayonne South. Take D932 direction Ustaritz, Cambo les Bains, Espelette, Ainhoa (border)

From Toulouse, Pau :

Highway A64 and A63 (Bayonne, Spain)
Exit Bayonne South. Take D932 direction Ustaritz, Cambo les Bains, Espelette, Ainhoa (border)