Well, if you look at the data sheet for the L297 controller, you see that one of the suggested circuit configurations (actually the first one) is using the L298 as the driver. You would have to hack the solarbotics module to have the L297 current limit with PWM. You would need to disconnect pins 1 and 15 from the board and somehow connect the flying pins to the rest of a L297 circuit because these are the sense output from the L298 driver that the L297 controller needs.