The script that handles the import from the LDAP directory is named "VI_PersonAuto_LDAP" and out of the box, it is only configured to bring basic attributes of a user object, such as First Name, Last Name, User ID or UPN etc.
It will be necessary to copy the default script and then modify it so that it will copy the additional attributes to the Person record. An example is below:
VID_PutValueSafe(Person, "CCC_CustomAttribute", Acc.GetValue("CCC_CustomAttribute").String)
With this line the value of ADSAccount.CCC_CustomAttribute will be transfered into Person.CCC_CustomAttribute.