Sounds a bit wierd...
Anyway, in your employee dim view create two columns - one that is Surname, FirstName & one that is FirstName Surname
Add these to your employee dimension (don't fortget to refresh the DSV) & hide the column you want to use as the sort (properties of the attruibute --> AttributeHierchyVisible --> False). Do you have an employee id? If so I would make that the key of the attrubutes
In the attribute relationship make your sorting column an attribute of your reporting column.
In the properties of the reporting column, change the OrderBy property to be AttributeName and OrderByAttribute to be the reporting column