"Pre" trigger

Hi @jaapjansma et al, I'd like to use CiviRules to make some changes to Contributions when they are created. I'd like to develop a custom Condition which makes use of the qfKey — a piece of data which is passed into hook_civicrm_pre but is not available from the "Contribution is Added" (post) trigger.

Could I create a new kind of trigger that uses hook_civicrm_pre? Or do you suggest I use the existing (post) trigger and pass the data from the "pre" hook to it somehow?