"Develop" - I think you mean "elaborate"?

With the Linksys, it is another interface. I think the default route is still the Wifi if you don't disable it or do route commands on xterm after you do the ifconfig eth0 and/or udhcpc commands.

1. Connect USB100M.
2. do "ifconfig eth0 up" (insert inet st.at.ic.ip here if you use it)
3. do "udhcpc eth0"
4. adjust routes.

Now you are connected via wired ethernet.

Someone mentioned how to create a "DEFAULT" interface for the connection manager in the "USB Networking" howto or wiki, so that might work too, as well as some other tips about how to modify the network config files.