Hello @YuSheng
You would have to overlay "/libs/granite/security/content/v2/usereditor/content/items/tabs/items/details/items/columns/items/col2/items/form/items" and append required items to it.
In the description you have mentioned custom login is used, so I guess you would be able to get details from the external system via API/Ajax.
Custom clientlibs can be added by overlaying /libs/granite/security/content/v2/usereditor/head/clientlibs
Aanchal Sikka