IBM distributes the TSM clients in RPM format, but not in deb format for Debian based Linux distributions. The re are some TSM clients in deb format out there, but the latest I could find is version 5.4. I found that alien converts the RPM files decently enough.
First, install alien:
sudo apt-get install alien
Then, get all the RPMs you want to install in the same directory and run:
alien -k *.rpm
There is a problem with the install scripts that they didn't create a link on my systems:
ln -s /opt/tivoli/tsm/client/lang/EN_US/dsmclientV3.cat /opt/tivoli/tsm/client/ba/bin/EN_US/dsmclientV3.cat
After that, the client should work just as if installed on a Redhat based system.