Debian has already set this up by allowing the user to specify their own spool directory as well as their own anacrontab on the anacron command line. They can then add anacron to their user's crontab and put a spool directory in their home. I suggest looking at the debian package's source code.
Steps to Reproduce:
err, why hasn't debian pushed it back upstream?
Anyway, I suggest to create a diff of the source code for maintainer review.