[Артем Enot Грунин]

Почитайте SDK как работать с lookup. Вот выдержка:

var lookupItem = new Array();

// This gets the lookup for the attribute primarycontactid on the Account form.
lookupItem = crmForm.all.primarycontactid.DataValue;

// If there is data in the field, show it in a series of alerts.
if (lookupItem[0] != null)
{
   // The text value of the lookup.
   alert(lookupItem[0].name);

   // The GUID of the lookup.
   alert(lookupItem[0].id);

   // The entity type name.
   alert(lookupItem[0].typename);

}