Success using the directions for both cases. Notes below.
If the package already exists, after using "manage depends and provides" to extend the package, go back to the package parameters page and use "Write an XML package specification to the packages/travlr/travlr.info file" to update the .info file.
"Subsite-convert-type" mystery solved. After a package extending subsite is created, a link for this action shows up on the "Main Site" administration page after 'Create new subsite.' There's a message key missing error (though this can be corrected using the translator mode in developer support).
To mount the package as a new subsite, just use 'Create new subsite' from Main Site admin. The form only offers the OpenACS default themes, but this can be changed later in the subsite's parameters.
Your script, new-oacs-theme-pkg.tcl, worked without problems after modification to use the local tclsh.
The only fly in the ointment: failure of the theming templates to pass the title <property> to blank-master.
foobar.tcl
----------
ad_page_contract {
Testing
} {
} -properties {
title:onevalue
context:onelist
}
set package_id [ad_conn package_id]
set title "Testing"
set context [list $title]
foobar.adp
----------
<master>
<property name="title">@title;noquote@</property>
<property name="context">@context;noquote@</property>
This returns the name of the package as the title, instead of "Testing."
I have an instance of xowiki mounted under this package subsite as well. The wiki pages do pass the title properly even though they use the same plain-master and blank-master templates (seen when using ADP reveal with dev support toolbar).