Setting Up Time Capsule as a wireless external hard drive

Question

I have a 2 TB TC that I wish to set-up as a wireless external hard drive at my office for my private files only not the entire company.  I would like for this to be private as well.  Here is my set-up now.
MB Pro late 2011
Connect to company network & internet via ethernet. 
I cannot connect the TC to company network - security reasons - company policy
I would like to use the TC as a external hard drive that I can access wirelessly for using Time Machine and backing up other image files from my scanner.
The problem is that when I setup the TC it is telling me to connect ethernet.  I can't because that is how I access my company network and internet.
Can this be done?  Thanks!!

Answer 1

But....in order to now connect to the TC via wireless, you will have to first unplug any Ethernet connection that may be present on your Mac.  
Or, if you do not want to unplug and replug the Ethenret cable, you could change the connection order to have your computer connect to wireless first and then Ethernet.
In this case, when you turn off the wireless on the Mac, the Ethernet connection will become active. 
The downside here is that you will have to turn the wireless back on to be able to back up or connect to the TC. In other words, backups will not be automatic unless you are connected via wireless to the TC.
There should be a way around this.
The issue is that the computer cannot use two gateways at once. It will either use wireless or ethernet. But in fact the computer does not need a gateway to communicate with the local network.
Follow Bob's instructions to setup the TC. But make sure the TC is using a different IP subnet to the main network.. eg.. main network is 192.168.1.x (which you can see from the ethernet IP address) then the TC on its default IP 10.0.1.1 is fine.. but if the main network uses 10.0.x.x which is fairly common, then swap the TC over to 192.168.1.1 for instance. It can be any value.. as long as not in the same subnet (ip range) as the main network..
Then on the computer.. keep the ethernet as the top connection.
Set the airport IP address manually.
Following the first example.. set the IP address to 10.0.1.10 with 255.255.255.0 subnet.
Do not set router IP or gateway or dns. (this is the most important part).
Apply all of that.
You should be able to detect the TC and connect to it. But it will not stop your main network working at the same time. And there is no link between them as long as you do not route it in the MBP.
Come back if you have issues.. or my explanation is lacking somewhere.
To do the setup it is usually required to do ethernet first and then you can unplug it.
If you have wifi in the office.. try and make sure you do not interfere. And set it manually with a different name for 5ghz.. and join only to the 5ghz network.. it will be both faster and less likely to cause interference to others. Most will not even see it. Set suitable password with wpa2 personal security so no one else can connect.