Currently, we have not implemented the ability to map additional Ldap fields to the Sitefinity profile fields. We have logged a feature request related to this and hopefully we will be able to implement this in our future releases. Here is the link
where you can see the description of the feature request and vote to increase its popularity.
It is not possible at the moment to add a custom logic to implement the mapping. The provider used by Sitefinity to connect to the ldap and pull the information for the users will not take any other information aside from the default fields.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items