SETUP_EXTERNAL_USER_ACCESS_MANAGE SETUP Endpoint
  /rpc/setup/?method=SETUP_EXTERNAL_USER_ACCESS_MANAGE  
  Object: 267. Click here for more information.  
  PARAMETERS TYPE  
  DataReturn Text A comma delimited list of advanced search fields to be returned after a successful save
  Id Numeric  
  Remove Numeric Pass '1' to remove the item
       
  AcceptSupport Text (1) Y/N [Default]
  Notes Text (2000)  
  TargetUser Numeric Mandatory. The user in your space that they are impersonating
  Type Numeric 1=Share Documents,2=Limited Access to My Data & Share Documents [Default],3=Support,4=Reporting Access,5=Pre-Authorisation,6=As Personal Space.

If you pass type=5 it returns the code that you will need for the second stage of authorisation
  UnrestrictedAccess Text (1) Y [Default]/N
  User Numeric See UserContactPerson
  UserContactPerson Numeric You need to pass either UserContactPerson or User. If you pass both, User takes precedence. The UserContactPerson / User is from the External User's space. They must be set as available.
  RETURN  
  id