This should be extremely simple and OOTB functionality that I hope does not require a Java Developer to code something.
We have a simple content approval workflow because we obviously don't want to risk Authors being able to use Activate and Deactivate, and delete directly. So those actions are done by the workflow as part of process steps. However, our authors need the ability to be able to schedule when pages activate and deactivate in a workflow. Ideally they would just use a calendar control of some kind to select the date and time for the page to activate or deactivate which ever the case may be. But if that is not OOTB then is there a way for the user of the workflow to specify a "Time Out" value from a participant step? Anything that requires a Java developer will cost us money so I'm hoping this funtionality is available in the product we already purchased, (CQ5.5).
See if  suffice your need. Otherwise based on use case might need some custamization required. In your custom workflow insert before the AutoTimeoutAdvancer step a new custom process step with a code that will set the metadata absoluteTime with the value in millisec.
WorkflowData data = wf.getWorkflowData();
data.getMetaData().put("absoluteTime", "<absolutetime>"); // <absolutetime> = calculated absolute time as a string.
 http://dev.day.com/docs/en/cq/current/wcm/page_publish.html#Scheduling a Page for Activation