Current situation is that you need to use the EAP controller to enable band steering on those EAPs which support it (EAP225/245/320/330). The TP-Link website claims in the comparison table of the EAP320 web page that EAP220 supports band-steering, too, but to my knowledge the EAP220 does not support it according to the specs on its own web page.

Since features like band steering are controlled by the software if the device supports it, changes are that future firmware versions will probably support it in the web UI, too. But for now you will need an EAP controller to use it. According to Tom's excellent article about EAP solutions, he writes:

If you want to know more about how Band Steering works and how to enable Band Steering on TP-Link EAP products, please see the EAP Controller User Guide (page 31).