Version 3.4.2 has a minor bug: Files in the Custom directory aren't read. This is the default place to put your own files to modify tclhttpd. This will be fixed in Version 3.4.3.
You can change the 3.4.2 version as follows:
In httpdthread.tcl, change
if {[string compare $f "pkgIndex.tcl"]}to
if {[string compare $f "pkgIndex.tcl"] == 0} {This page should be deleted when V 3.4.3 is released.
While this works in terms of sourcing files in the custom directory when tclhttpd starts, I wasn't able to source them through the debugging URL (/debug/source?source=foo.tcl). I found that I could fix this by placing the following in httpthread.tcl:
Doc_TemplateLibrary $Config(library)
-WJR