Does such a thing exist?  I need to be able to hardwire the NVR box to the computer but then have the signals sent wirelessly from the camera to the box.  This is in an office building that does not have wifi set up for security purposes.

Anything that transmits the video wireless will have the basically the same security risks as traditional "wifi". Bluetooth, zigbee, rf, whatever. Plus if you can even find cameras that support it, I'm sure they would be significantly more expensive.

If your security department is reasonable, I'd explain your problem to them and see if they would be okay with setting up a separate wireless network that did not connect to the companies network. That would take away a significant amount of the risk for which they probably have that rule in the first place.

http://flyteccomputers.com/brand/EZ-Bridge

You can setup a separate network just for the camera system

Leave it off the regular network and there is no risk of intrusion to your real network, and very unlikely that someone could get into the camera system

Need to tie it into something else like internet, you simply have to choose your risk. VLAN, separate internet provider, just choose your level or risk/cost/ease of use

You can set up a basic cheap wifi router for just the cameras and not hook it to the Internet or the company network.  Just hook your laptop and the cameras.  Set it up, then go in and turn off the ssid broadcast so the network isn't easily discovered.