Remember that if you add a DAE-ATA to a CX4-240, what ever bus you add it to will only run at 2G since that is the max that DAE is rated at. As for the DAE2P, that will depend on the speed of the drives you have in it. if the drives have the 2G/4G sticker then your good.
The DAE will not be recognized in the above mentioned scenarios until you perform a "Bus speed reset wizard". that requires that the hosts be offline and the whole array be rebooted.