CCK Date Module

I need someone to quickly customize the CCK Date Module, or create a module that would allow the end time to be predefined based on the start time entered. Therefore the user would have to select a duration or increment of either 1 hour or 1.5 hours. Then the end time should automatically be selected and disabled preventing it from being modified.

Example:
Start Time: 1:00pm
Increment: 1.5 Hours
End Time: 2:30pm

I need this done ASAP, please submit your quote. Thank you.