Well, I thought it is useful for others to share my experiences with Rpi and Huawei E353.
I struggled for a while with the dongle and latest wheezy. To get it working, what I did was basically just:
-Install usb modeswitch (sudo apt-get install usb-modeswitch)
-Edit /etc/network/interfaces and add this line: "iface eth1 inet dhcp"
Then the eth1 (if you only had eth0 before), will have IP-address, probably 192.168.1.100 or 192.168.1.1 or something similar. Check it with "ifconfig". Then simply add default gateway "sudo /sbin/route add default gw 192.168.1.100 eth1".
To share the Internet connection, do similar script (and execute it):
sudo iptables -A FORWARD -i eth0 -o eth1 -s 192.168.0.0/24 -m conntrack --ctstat
e NEW -j ACCEPT
sudo iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
sudo iptables -A POSTROUTING -t nat -j MASQUERADE
/sbin/iptables-save > /etc/iptables.sav
sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
I now have a camera surveillance system with controlled camera electricity outlets (via gpio and standard remote controlled outlets). System has much lower power consumption than the previous system.
All is solar powered