My pack is the High peak alpamayo 55:
http://highpeakusa.org/pages/alpamayo_pg.html

I am wondering where I would carry a fly fishing pole? Or what would I rig up to carry one?

Break it into small enough pieces, and it should fit in the top pocket nicely.

I'm not a fly fisherman, so this may or may not help.

I remember reading that Colin Fletcher once took some PVC pipe from a plumbing supply store, put a cap on both ends (I'm not sure if it would need to be threaded, or if you'd just glue the bottom on and friction-fit the top), put the sectional pole inside, and lashed it to the side of his external-frame packc. I'm wondering if you could use the same idea, securing it to the side of your pack using the side compression straps and outside pole pocket. (I didn't spend a lot of time with the photo - I thought I saw a pole pocket on the side of the pack.)

Perhaps a store like Cabela's would have something like this ready-made?

Put it in a tube and strap it to the side. Get a pole that at least breaks in half. You can make tubes with PVC (schedule 20 or thinner), or buy one at a fishing store.

Even thinner and lighter than PVC...fluorescent light proctor tubes. Clear plastic, available at any hardware store near the light bulbs.

Exactly. And my pack actually has a "sleeve" between one of the side pockets and the pack itself...so I just slide the rod down there and snug it up tight.

How many pieces is your fly rod?

I have a 2 piece fly rod. The loops on the pack are meant for ice picks I think. They are too small to try and thread a fly pole tube through.

well let's start with the type of pole that you are going to carry. There are backpacking specific poles that break down into 5 or 6 sections. If you have a pole like that you can store and carry it almost any where. If you have a pole that only breaks down into two or three sections you can carry them similar to how you carry your hiking poles when they are not being used. Your pack may have accommodation for this or they can easily be fabricated to carry your pole. I never go into the back country without mine if I know that I will run into a stream or two. I have caught my dinner many times and it will all give you a small sense of accomplishment out in the wilderness. If you fly fish, usually the poles are considerably longer a may present a bigger problem, but there can always be some accommodation that can be made to your pack that should carry most any kind of pole that you want to carry. I do a lot of fly fishing on lakes in the area that I live in and have had a lot of success catching a mess of blue gill and filleting them. 8 or 10 of these can make a seriously delicious meal, and again, it makes you feel great because you caught it all on your own...sabre11004...