There is a but leaving from Oloron-Ste. Marie passing through Urdos. Unfortunately I cannot remember where I found the bus schedule... when I used it my self 2 years ago. - Urdos is a VERY small village (hamlet)... I am sure that the Hotel there can help you call a taxi... however it might a long wait... but I am sure it is posible.
I was told before I went that the view walking from Urdos to Somport is amazing... and I really wish I did it... as walking from Somport to Jaca is DOWN all the way... if you have weak knees or any knee problems this is not the best way to start out... I got a knee problem walking down from Somport... wishing I had "warmed up" from Urdos...
When you arrive to the Albergue in Artieda - give the old woman who is running it a big hug from me, she is absolutely wonderful.
...and If you feel like it this should be worth seeing:
http://www.monasteriosanjuan.com/ingles (I didn´t due to the bad knee I got - another thing I missed, but wanted).
what ever you choose I wish you a buen Camino.