Use sp_drv_unitext_locator_setdata which accesses the Transact-SQL function setadata.
sp_drv_unitext_locator_setdata locator, offset, new_data_locator, data_length
locator –a unitext_locator that references the unitext column to insert into.
offset – an integer specifying the position from which to start writing the new content.
new_data_locator – a unitext_locator that references the unitext data to insert.
data_length – an integer containing the number of characters written.
None.
