In ITIM , it is very easy to customize various forms like person add.
Steps:
Login to itim console
Navigate to Configure System -> design forms
You may have to accept running the script, as this is java. If you dont let the script run, or let the browser stop it , then you might not be able to customize the person page.
Now go to Person , double click on it.
You will see person again , if you have made another custom person class, you will be able to see it there as well. Once you double click person, you will see the tabs on the right. Each tab has different attributes. Each tab in here appears as a separate tab in create person.
To create a new tab, go to Form Menu --> TAB menu -> add Tab.
You will then need to rename the tab by tab menu -> rename tab
Once the person form is created, simply double click the attribute you want from the attribute list on the right. Any attribute you dont want to show up in the user create menu , can be selected and deleted using delete key. this will send the attribute back in the attribute list. You WILL NOT BE ABLE TO DELETE ANY ATTRIBUTE, so dont worry and play around.
You can give default value to the selected attribute by selecting Properties in right hand corner of the window.
Once done , save form and exit.