Function with table%ROWTYPE globbing

Postgresql 8.0.4 using plpgsql

The basic function is set up as:
CREATE FUNCTION add_data(t_row mytable) RETURNS VOID AS $func$
DECLARE
    newtable text;
    thesql text;
BEGIN
    INSERT INTO newtable thename from mytable where lookup.id =
t_row.id;
    thesql := 'INSERT INTO ' || newtable || VALUES (' || t_row.* ')';
    EXECUTE thesql;
    RETURN;
END;
$func$ LANGUAGE plpgsql VOLATILE;

SELECT add_data(t.*) FROM mytable t where ....
ERROR:  column "*" not found in data type mytable

Now I have tried to drop the * but then there is no concatenation
function to join text to a table%ROWTYPE. So my question is how can I
make this dynamic insert statement without listing out every
t_row.colname? Or, alternatively, is there a better way to parse out
each row of a table into subtables based on a column value?

Sven