For those that are interested, I have now migrated my development system to Joomla 1.7 and have begun the process of making Huru Helpdesk v0.89 Joomla 1.6+ compatible. 

My plan is to release the 1.6+ compatible version as an update to v0.89 since the features will be identical (all features are frozen for the modifications).  Unless I run into something that makes it impossible, the plan is to make the update dual installable on Joomla 1.5 and 1.6+.  In the future, I hope to keep it compatible across all versions for as long as Joomla 1.5 is supported.

As for a timeline, I am guessing that the modifications will take a couple of weeks.  

I would like to thank AmrasTaralom for posting a Joomla 1.6 compatible mod of Huru v0.88d a few weeks ago.  That should provide some good info going forward with the modification of Huru v0.89.