my $sql = 'DECLARE @ptrval binary(16);'
        . ' SELECT @ptrval = TEXTPTR(item)'
        . ' FROM table '
        . ' WHERE whatever criteria;'
        . ' UPDATETEXT table.item @ptrval NULL 0 ?';
$dbh->do($sql,{},"new text");


##</code><code>##

CREATE PROCEDURE dbo.APPEND_THINGY
@id int,
@new_text varchar(8000)
AS

DECLARE @ptrval binary(16)
SELECT @ptrval = TEXTPTR(item) 
   FROM table 
   WHERE id = @id

UPDATETEXT table.item @ptrval NULL 0 @new_text;

GO

##</code><code>##

my $sql = q{exec append_thingy @new_text = ?};
$dbh->do($sql,{},"new text");