I suspect I'm being really dim (as usual)

I have a primary key which is a supplied value from a data import -
basically a clients internal stock id for a "product".

How do I persuade Transfer to let me set my own key?

I've tried :
<id name="ID" column="StockID" type="numeric"  />
and
<id name="ID" column="StockID" type="numeric" generate="true" />

The first throws a  SQL error because the insert is not including the ID in
the INSERT statement, as the database requires a value and there is no
default set for it.
The second inserts an incremental ID that Transfer is kindly generating and
not inserting the ID that I set using objProduct.setID(blah)

I'm using Winders, CF8, MySQL 5.x and the latest Transfer from SVN.
I did try reading the docs and searching, but don't seem to be able to hit
on what I'm after.  The stupid thing is I'm sure I've done this before, but
can't find it, nor can I remember what I did!

Thanks for the help

Regards

Stephen