How to modify the update command to omit a rowguid column

[JDS]

I have a table with the primary key as a uniqueidentifier / GUID and
the rowguid property set (it is used for replication). When creating a
data table in a dataset in VS2005 the table adapter update command is
automatically generated but when I try to use it I get an error saying
that "updating columns with the rowguidcol property is not allowed". I
have tried setting the field as read only and regenerating the auto
generated direct DB commands but this does not help; it still includes
the field in the update command.

I have also tried editing the update command directly but when I
remove the relevant field so it is not in the SET field list I get an
error saying that one of the other fields is missing when I try an
update. I have also tried editing the parameter list but, again, this
does not solve the problem.

In another attempt as a solution, I tried creating a custom update
command for the table adapter. However, this produces an error when I
try to write a null value to one of the fields despite the underlying
SQL database field being set to accept null values. I could check for
null for each of the fields before performing the update but this is
going to be incredibly inefficient and require a lot more work than
should be necessary.

(using VS2005 and SQL Express 2005)

Any help greatly appreciated.