Adding a Second wireless access Point to a Network

Yes.

The WNR2000 has a setting under ADVANCED > Advanced Setup > Wireless AP to set it up as an Access Point.  The instructions should be straightforward.  You will connect the WNR2000's yellow, Internet port to your CenturyLink router.

The method you used (i.e. disabling the DHCP server) is old school.  You should still be able to use it but there are a couple of differences.

1. You must connect a WNR2000 LAN port to the CenturyLink.  The Internet port should be left unused.  The reason is that the WNR2000 is still in router mode, so the Internet port is considered a WAN port.  Wireless AP Mode differs from this because it disables router mode and converts the Internet port into another LAN port.
2. The WNR2000 must be configured with a static IP address.  You did this by assigning 192.168.0.4.  But you need to make sure this address is 1) in the IP subnet configured on the CenturyLink and 2) not in the DHCP range managed by the CenturyLink.  Both conditions must be satisifed.  Wireless AP Mode also differs because it has an option to use DHCP to obtain an IP address from the CenturyLink for the WNR2000 to use.  You can, however, use a static IP address in Wireless AP Mode.  You will see the two options if you explore the Wireless AP Mode setting.