Cisco WAN :: Can Separate Or Pass Through External IP Through 1841

Our bank is required to do disaster recovery testing. We are doing this offsite at one of our director's businesses. His setup is as follows: His ISP is Time Warner which provided him with a wall unit and a switch He has a Cisco 1841 router out from the Time Warner switch and then down to his internal network, so TW wall unit --> TW switch --> Cisco 1841 --> internal network.The IPs provided to them from TW are 74.219.xxx.1-254 We are trying to use the external address of 74.219.xxx.222, which his business is not currently using internally The Cisco 1841 router holds and NATs all of these addresses currently. We have a Cisco 800 series that is a dedicated router that needs an unused external static IP setup separate from their network. We were trying to plug into their Cisco 1841 and give the 800 series an internal address of 192.168.xxx.222. This will not work for our bank's core processing data center. It has to be out of the TW switch and have an address of the 74.219.xxx.222.
 
We tried plugging into the TW switch and making the 800 series router parallel to the 1841 router. Communication is not functioning when set up this way. This was tried on a laptop before using the 800 series router. Is there a way to pass through the 74.219.xxx.222 address internally through the Cisco 1841 so we can connect the 800 series directly to this address and the 1841 doesn't use or NAT it in any way?
 
We had contacted TW support and they made it sound like we would have to block out some addresses and resubnet our director's network. This probably will not be an option. Basically we need to pass the 74.219.xxx.222 addresses internally and have the Cisco 1841 pretend not to see it at all.So we would like to have 74.219.xxx.1-254 into the TW wall unit --> TW switch --> Cisco 1841 --> all 74. addresses resolved to 192.168.xxx.1-254 to internal EXCEPT 74.219.xxx.222 which would pass through to the Cisco 800 series router.