Yes you can set one of your older routers as an AP mode router then plug cable from that wan to normal plug into Comcast router (like a PC would be)
and set WIFI ID the same as other router (or not) with password , and your set.
I did a quickly check on your netgear but did not find information on the manual
http://www.downloads.netgear.com/files/wgr614v5_ref_manual.pdf
but basically Follow these simple steps:
Make sure there are no network cables attached to the WGR614 (neither LAN nor WAN)
Make sure your laptop or PC used in the following steps is not connected to the network
Connect your laptop or PC to any of the LAN ports of the WGR614 using a network cable
Log on to the WGR614 via your web browser (usually 192.168.0.1 or similar – check the manual for correct address and default logon credentials)
Disable the DHCP server of the WGR614
Change the IP address of the WGR614 to something else than the IP address of the router
Connect the router to any of the available LAN ports of the WGR614 using a network cable
Configure the SSID on the router and the access point so that they are the same
Configure different wireless channels on each device (use the non-overlapping channels 1, 6 and 11 to avoid interference)
Configure the WGR614 to the same security level and settings as the router, including the access control list
Separate the devices to the edge of their wireless ranges
Please consult the manual and/or the Netgear Support Pages if you get stuck in any of the above steps. The network DHCP server IP address range on the router must not include the IP addresses reserved for the access points. If you have the router (that is connected to the Internet through its WAN port) on IP address 192.168.0.1 and, say, two access points on 192.168.0.2 and 192.168.0.3 respectively, the DHCP range on the router should start with 192.168.0.4 (and end with whatever number you think you will need for your network attached gear). Understand that having duplicate IP addresses on your network will put you in a situation you don’t want to be in, so take steps to ensure that the router and the access points never have the same IP. Note also that this setup will not extend the WLAN range of an unthreaded network, i.e. the access points must be connected to the router via cables in this solution. If your aim is a wireless-only network, you need to look in to access points with repeater functionality.
Tip: If the router is configured with the internal IP address 192.168.0.n on the LAN try configuring the access points with internal IP addresses that are easy to remember, such as 192.168.0.n+1, 192.168.0.n+2, etc.