Originally Posted by qualiteam
In order to add this feature you can try the following modification (patches for X-Cart 4.4.4):
1. Apply the attached PATCH.sql
2. Apply the attached DIFF.patch
See the attached snapshots.
Once the patches are applied new options will be available on profile options page in admin back end and customer front end.
New "Address book" fields will appear on checkout and address book pages.
See the attached snapshots (next posts).
Note: Only default build-in fields can be used for shipping calculations.
Here is a patch adjusted for version 4.4.5: