Hi Karen-
I definitely could be wrong here, but I think they have remarked the Norte so that it doesn't go through Hondarribia anymore. When I followed the yellow arrows, they led me out of Irun and then straight on to Pasajes via the hermitage.
That's not to suggest, of course, that you couldn't still go that way, and I bet you would find yellow arrows once in Hondarribia. But, I think you'll be trading some nice off-road walking for a lot of highway. If you just want to see the town, you might consider taking a taxi/bus to it, having a look around, and then returning to Irun to start your walk.
As I said, I might be wrong, and I hope someone will correct me if I am. I know for sure, though, that the walk straight from Irun to Pasajes is a great one!
You'll have no trouble reaching Pasajes and I really doubt you would have a problem making it to San Sebastian. Reserve a bed ahead of time and enjoy the walk.
Dave
PS - My advice to those looking to trim off part of this route is skipping the section between Bilbao and Santander - lots of road walking and less interesting things to see than before and after.