you might just want to statically configure the printer's ip address. Most of 2wire's products default to a device address of 192.168.1.254. If you give your printer a 192.168.1.250 address with a default gateway address of the modem (ie: 192.168.1.254) - you should be working.....
you didn't mention whether your computer is able to connect, if so, what is your computer's ip showing as?
This is correct. Also make sure to use the same subnet for all machines.
An IP address generally has 3 parts
1) the device address. as above, this would be 192.168.1.250
2) the subnet: for this ip using 255.255.255.0 would be okay.
3) the gateway address which is usually the address of a router.
The gateway address is optional unless the device ever needs to communicate with the gateway in which case it is mandatory. To determine the gateway address, go to your computer, open a command window and type ipconfig and then hit the Enter key.
Ipconfig will return the address, subnet and gateway for your computer. In small networks almost all use the same gateway address. So whatever you find for the gateway address of your computer is about 99% chance of being the same as needed for the printer.