Hello
There are some woodwind parts sites on the web, like this one (never used it, no endorsement):
http://instrumentclinicusa.com/index.ph ... page&id=13.
The critical dimension is probably diameter, you'll need a caliper/micrometer to be accurate.
Anthony Baines in "Woodwing Instruments and Their History" mentions using a sewing needle of the right diameter, cut to length, ends hammered flat (to catch in post), tempered blue (not sure how to do that), and slightly bent with pliers for bias.
I have an Adler tenor (low C key only) so I see what you need. Doesn't look too hard to do, but patience is the key (for fixing the key).
FrankP