It can be done by creating a BVI (bridge virtual interface) and then assigning the ports you want to switch to the BVI. The BVI still must be assigned an IP address, but if you didn't do that, you couldn't manage the switch.
The relevant system-level commands are:
bridge 1 protocol ieee
bridge 1 route ip
To create the BVI:
interface bvi 1
ip address ...
To add an interface to the BVI:
See this link for information about disabling spanning tree and enabling portfast. You may need portfast to get DHCP/PXE to work in some cases.
Note that the I make no promises about what kind of performance you'll get with this configuration. This is just not what this device was built to do.