Nevím, proč byste to proboha chtěli, ale je to možné:
DELIMITER //
DROP PROCEDURE foo//
CREATE PROCEDURE foo(IN MYTABLE varchar(50) , IN COLNAME varchar (50), IN MYTYPE varchar(50))
BEGIN
SET @ddl = CONCAT('alter table ', MYTABLE, ' add column (', COLNAME, ' ', MYTYPE, ')');
PREPARE STMT FROM @ddl;
EXECUTE STMT;
END;
//