Thanks for joining here in the thread, @vaiconsultant. I've got some information for you about adding hours to a project in QuickBooks Desktop.

While we can simply add hours to a project in QuickBooks Desktop with you as an employee, the ability to let it show on your job costing reports isn't available. Since you won't be paying yourself as you have your own way of doing it, we can't tag it as Billable when recording it, causing this activity not to be included in your reports.

I can see how you would want to achieve this in QuickBooks Desktop, however, this is the default of the program. 

On the other hand, you can consider looking for a supported third-party application that'll enable you to create job costs using time entry data only, making it not billable. You may refer to this article to find one: Apps help QuickBooks run better. I'd suggest searching for keywords to maximize the results and taking the time to read the customer's Reviews for better recommendations.

I've also added this article that can provide you with some insights in case you'd want to add, edit, and delete items: Add, edit, and delete items in QuickBooks Desktop. 

I'm still willing to provide more information if you need some with tracking hours worked by job in QuickBooks Desktop. I'll be sure to get back to you. Have a great day ahead.