I'd go by bus from Bilbao to Pamplona, then another bus to Roncesvalles then a taxi:
Bilbao - Pamplona:
BILBAO - PAMPLONA
COACH:
Company: “La Burundesa”. Trip takes 2 hours.
The timetable from Bilbao to Pamplona is approximately:
Origen Salida Destino Llegada Tarifa Ruta
* BILBO/BILBAO 07:00 PAMPLONA/IRUÑA 09:20 12,45€
* BILBO/BILBAO 10:00 PAMPLONA/IRUÑA 12:00 12,45€
* BILBO/BILBAO 13:00 PAMPLONA/IRUÑA 15:00 12,45€
* BILBO/BILBAO 15:30 PAMPLONA/IRUÑA 17:30 12,45€
* BILBO/BILBAO 18:00 PAMPLONA/IRUÑA 20:00 12,45€
* BILBO/BILBAO 20:30 PAMPLONA/IRUÑA 22:30 12,45€
Departures: Garellano Station. The trip takes approximately 2 hours.
The connection between Bilbao airport and the bus station (in the city centre) can be made by taxi. Approximate price: 20 Euros. Or by bus: Price: 1.15 euro. Departs every half hour from the airport (arrivals area) and from the bus station. It takes approximately 25 minutes.
More information on: +34 948303505 or
http://www.laburundesa.com or
jochoa@laburundesa.com
There is a bus at 6pm every day from the bus station in Pamplona to Roncesvalles.
From Roncesvalles get a taxi accross to St Jean - taxi numbers in the CSJ guide or on the noticeboard of the hotel next to the Monastery.
See:
http://www.csj.org.uk/planning.htm
Buen Camino
John