To enable Client mode (to bridge an existing WiFi network to Ethernet), follow these steps:

1. Flip the switch on the ZyXEL's side to AP mode
2. Save a backup of the current configuration & settings
3. Configure your PC with a static IP such as 192.168.100.22
4. Log in to the ZyXEL's setup page at http://192.168.100.1
5. Save a backup of the current configuration if you wish
6. Click Wireless → Basic Settings
7. Click Wireless Mode → Client (drop list)
8. Click Wireless → Site Survey to refresh the list of WiFi networks in range
9. Select your network (SSID) and then Next
10. Select your encryption method and enter your passphase
11. Click finish

Something I didn't know before but the configuration document pointed out, in client mode BOTH Ethernet jacks pass through the Internet connection. SO, end result, I do (and you will/would) have a travel router that serves up a 150mbps WiFi N signal, an access point, AND a wireless client bridge that allows two devices to connect to a wifi network.