of course it won't work
cause N900 can handle it's connection to the router only
and won't create another interface for qtmobile hotspot

what you need is TOR to be working with whole ubuntu

here's how:

gnome:

Gnome System —>Preferences —> Network Proxy
*click on Manual proxy configuration
*use the same proxy for all protocols
enter http:
127.0.0.1
port 8118

------------
KDE:

KDE Computer —> System Settings —> Network Settings —> Proxy tab (On the Left panel)
*manually specified proxy
> setup
*apply all protocoles
http:
127.0.0.1
port 8118

still need to set your browser to use TOR