The "missing" script in the 0.5 distro seems to have
the wrong version. As reported by jscheid:
//N/downloads/texidoclet/texidoclet-0.5/missing:
Unknown `--run' option
Try `//N/downloads/texidoclet/texidoclet-0.5/missing
--help' for more information
configure: warning: `missing' script is too old or missing