Hi Jason -
There are all kinds of "training" regimes that folks will suggest for you.
At worst, some training programs may make you susceptible to injury, at best, they will not prepare you for the repetetive 20+ days of walking on varied surfaces and grades.
In my opinion, the best way to train for walking the camino is walking.
For your ankle and knee, I suggest you see a physiotherapist to see what s/he suggests.
So just get out and walk - after the first week, walk with your pack and try to include hills and varied landscape. If you intend to use poles, practice with them as well.
Best of luck,
lynne
Also: I walk at about 4 kph on the camino - sometimes 5 for very short periods. Believe me when I tell you that is sufficient to complete your stages in a reasonable time every day. I have seen tall young guys walking 5-6 kph and they were really moving! You can keep this pace up with no problem for your whole camino, but I wouldn't push for more than l4-5 kph.
L