pkg_mkIndex . *.tcl *.so
The -verbose option can help point out what properties of your files are giving the [pkg_mkIndex] command trouble.
pyk 2012-11-02 - dgp stated on the irc channel today that pkg_mkIndex is not generally a good idea. It can't possibly solve the problem right for any but the most simple packages, and even for those, typing the index script yourself is just as easy. For automatic maintenance of version numbers, etcl, construction via configure or Make is a better answer. The problem pkg_mkIndex has to solve seems simple in concept, but is in general impossibly difficult, primarily because of the very Tclish design decision to make its packages implicit rather than explicit.
"Think of pkg_mkIndex as at best a (poor) tool to help you write pkgIndex.tcl files. If you can do a better job by hand (or by template substitution during configure) then that is probably better." -- dkf ,tcl-core mailing list ,2012-11-07