How to enable battery management IC
Ok, if I understand your question correctly you are trying to determine the proper configuration of the CE pin for your project. 
From the datasheet:

From this I can interpret the function of this pin as enabling/disabling standby mode. In this case the chip will not be managing the system power path as well as not charge the battery. If you do not need standby mode you can tie this to a common cathode diode array such as the BAT54C or similar such that the two anodes are connected to either power source. I agree with your closing comments in the question, not too complicated as its a single 3-pin device. I hope this helps!