Install IBM Installation Manager without internet connection or connection with proxy

When you try to install the IBM Installation Manager, and you have no internet connection, or there is a proxy standing in your way, it is possible that you cannot enter any repositories, because the installer does not get launched. It seems to get stuck at trying to connect to public.dhe.ibm.com.

We encountered this when  we tried to install WebSphere Business Monitor. After installing WebSphere Application Server 7, the installer tries to merge the was7 it just installed into a new installation manager installation (if it was not yet installed). 

This IBM document describes the problem : http://www-01.ibm.com/support/docview.wss?uid=swg21420545#NoInternet , here in combination with Process Server 7. The suggested workaround (pre-installing the ibm installation manager with the -input parameter after editing the install.xml file) did not work. Somehow, he still had a reference to the online repository.

Luckily we found a workaround (by accident). When giving an invalid -input parameter (that is, to a file that does not exist), the installation manager installer gets launched without trying to connect to a repository! Now you can unflag the online repositories using the gui, add the repository.config file of the installation manager disk, and install the installation manager.