The Nissan Path

The speedometer cable in my '90 Pathy (3.0 engine) needed replaced. Got the new speedometer cable and it is just about installed. The cable is hooked to the transfer case and routed under the hood. I noticed the spot where the cable goes through the firewall is incredibly hard to get to, to the point where it is impossible to even get my new cable installed without breaking the head off. I popped the head off of the old cable when I pulled it out. Any advice on getting this in there correctly? I'd rather not break a $70 part and I really do not want to remove the entire upper intake assembly just to get to the hole. I may have to bite the bullet and have a garage do it for me.

Thanks for any help you can offer!