rules ubercart

I have a customer that is requesting that a checkbox on an administrative form in ubercart be checked automatically on page load. I have used rules to alter forms before but wasn't sure if this was possible.

I tried setting up a triggered rule for "Uc cart checkout form is being built", with the action of "Set Default Value of Form element" with the values; 0, 1, Yes, Checked & On. None of these settings worked.

Can anyone please point me in the right direction on making this happen? Thank you for taking the time to read my question.

http://www.ubercart.org/forum/development/5555/rules_vs_conditional_actions

Maybe we can team up and try to re-raise the support in rules...