How to install Remastersys?

I want to install Remastersys, but I get the following error:

$ sudo apt-get install remastersys  
Reading package lists... Done  
Building dependency tree  
Reading state information... Done  
E: Unable to locate package remastersys

Searching for Remastersys in Software Center also doesn't give proper results:

I have tried following these instructions and have added Software Sources as shown in the following screenshot, but I still get the same error:

Solution 1:

Use remastersys.

http://www.remastersys.com/ubuntu.html

Please read the instruction carefully.

1. In Firefox, go to :

   http://www.remastersys.com/ubuntu/remastersys.gpg.key.

   save file as text someplace where you can find it.

2. In synaptic, go to Settings/Repositories; select Authentication tab and Import Key File just downloaded.

3. Still in synaptic, go to Other Software tab and click Add, then enter the apt line

   deb http://www.remastersys.com/ubuntu oneiric main

4. After adding it, a new apt line will automatically added ended with Source. You need to uncheck it

5. Leave the repositories tab and "Reload".

6. Search for remastersys and select for install. Edit/Apply Marked Changes.