Unfortunately, this isn't possible using specifications. You'll need to create custom attributes on TICKET and then modify the application using the MAF configuration to display those attributes (similar to how description and other fields are provided today).
I am not sure why IBM implemented the new specification type (dates weren't possible until relatively recent) as a simple date field rather than datetime. If you open TICKETSPEC in database configuration and look at DATEVALUE you'll see it's set as a data type of DATE rather than DATETIME. This means storing a time is impossible and Maximo will not adjust the date for time zones. For some specifications this makes sense. But on the SR scenario especially (which is why the DATEVALUE specification was added) there are a lot of scenarios where you want to capture an exact time from the user.
