Internet sharing, vpn and chromecast

I would like my chromecast to go through my vpn. I cannot configure the chromecast to use my vpn (if you know how please let me know) so I thought I could have it go through my MacPro using internet sharing. My MacPro does not have a wifi card so I use a wifi dongle, which has worked great, but since my MacPro connects to the internet wirelessly and my TV/Chromecast is in the living room I cannot connect the Chromecast to the MacPro wirelessly.

I have an extra wifi dongle and I'm wondering if I can use both dongles on the computer: one for connecting to the router and internet and the other for sharing my internet connection and therefore my vpn on my computer.

Do you know if this is possible? If so how? Do you know of another solution for connecting a chromecast to a vpn?

Cheers