Hi Jon,
two options.
A) Get the HEAD version of acs-tcl. Or at least 5.3. It is save to run in a mixed environment (e.g. acs-kernel and acs-tcl in 5.3, rest on 5.2).
B) Copy the procedure from acs-tcl 5.3 into your installation
C) Install contacts only once and rename to call to apm_package_id_from_key
Existing users will be automatically converted to contacts by a scheduled procedure.