As CAS Proxying is not an obvious authentication to set up, here are
some documented examples showing how a foreign application can query
koha webservices, being CAS authenticated.

The starting point is proxy_cas.pl

To find more about how CAS Proxy works :
http://afs.berkeley.edu/~lr/presentations/cas-auth/
http://www.ja-sig.org/wiki/display/CAS/Proxy+CAS+Walkthrough