How to create a private wireless network off of public wifi?

Question

My question is somewhat similar to this one, but that was never answered. Mine is different enough that I believe it warrants a new question.

I am an organizer for an event coming up and we have some unique networking needs. During the event, all of our administrators require internet access. This internet access is provided by public wifi (for example, in the event hall) or by 3G wifi hotspot devices. We would like run a private wireless network off of a personal router that has a printer and hard drive but that is also connected to the internet. Configuration would look like this:

Public/hotspot wifi
    |
  (???)
    |
Router (ASUS RT-N65U) -- Printer & Hard drive
    |
 Users Connected to Private Wireless network

One possibility is to use a computer to connect to the public wifi, and then bridge this connection to an ethernet output connected to the router. However, if I understand correctly, this computer would not be able to access the printer and shared hard drive because it is plugged into the "internet in" port on the router.

What is the best way to set a network like this up?

Something that may be relevant, there is no DD-WRT firmware available for the given router, but there is another option for 3rd party firmware.

Answer 1

I'm in the same delima looking for an appliance that will connect to an open wireless and create a separate private network, most extenders only extend that one network getting ips through DHCP from the initial wireless device, an access point would be great, but I've never found one that isn't hardwired to the initial device handing out again IP's, only thing I can think of is a dedicated PC with 2 wifi cards maybe the linux firewall on a floppy in an extra box. I'd rather not dedicate an old box or always on unused laptop with a second usb wireless card?