Just recently it was decided to no longer support ant 1.6.5. I believe that the missing file you refer to was also part of the reason this version is not supported.
On 6/28/07, Manveen Kaur <Manveen.Kaur@sun.com> wrote:https://jsftemplating.dev.java.net/source/browse/*checkout*/jsftemplating/lib/external/README.txt
1) Mentions you need to copy apt-ant.jar to ant lib directory. However
there is no apt-ant.jar present under lib/external.
2) Also I tried compiling with ant 1.6.5 but was getting the error:
/home/ws/jsftemplating\build.xml:96: Could not create task or type of
type: apt.
It worked with ant 1.7.0
It would be good to update the README.txt with the latest instructions.
--Manveen