Hi,
your user name is added, so that your own packages has a higher version number than the original version. This is necessary, if you want to upgrade a System with your own packages.
If you want to install your own packages in a running system, the easiest way is to start a devel server. Simply checkout the develserver sources ("make checkout name=develserver" in the MLD folder) and do a "make start" in the develserver folder.
Now you can install your own packages e.g. by webif packagemanager.
To disable the search of own packages, simply remove your name in the file /etc/rc.config from the APT_DEVELOPER setting.
Claus