I’m doing something similar, check out this link.
You have to upgrade your routers firmware with either dd-wrt or tomato (your choice). Once you’ve done that, you can turn your router into a wireless repeater or let it connect to your network and act as a regular router! Then just connect your computer to the router with your regular ethernet cable.
The image of the Linksys does not identify the model, but most Linksys models do not include WiFi client functionality – which is what is needed for it to connect to a WiFi network. Some Linksys models can be “modified” with non-Linksys firmware which enable them to have WiFi client functionality.
USB WiFi adapters/dongles can be found for around $20 or less these days.
Get your laptop connected, then change the Ethernet port on your laptop to a VPN. Set it to share the network connection with other computers, then plug it to your WAN port – and there it is.
Those MiFi’s are capable of being used as a direct tether via USB which makes it show up as an Ethernet device. This would be the best and easiest solution.
1. Access the Administration Web Interface. (Connect via Wifi, then go to 192.168.1.1 in a web browser)
From the Advanced tab, click Settings.
From the Router section, select USB tethered mode.
Note Enabled when a check mark is present.
Router section with USB tethered mode
Note The device restarts.
Connect the device to the computer using a compatible USB cable then launch a web browser.
Note If applicable, allow adequate time for the computer to detect the device and install the necessary software.
Note The device is setup and functions as an ethernet connection (no connection software required).
This will required the MiFi’s driver to be installed, which should appear as an installation disk when you connect to the MiFi via USB