One method is to copy client files from other RPM based linux to Ubuntu. There are some postininstall scripts which are executed after normal RPM installation. The second method is to put client installation RPM on Ubuntu host and run from console mc (Midnight Commander). mc is a "norton commander" looks like tool. Go to the folder where the rpm with client binaries is located, point to this rpm file and hit . MC got something which is called rpmfs (or something like this). So you can browse rpm like a regular folder. Copy all binaries to the location which you will see in the rpm file (some files will go to /usr/bin some of them to /usr/sbin and other to /usr/lib). Then find inside the RPM directory with scripts (there should be files called POSTIN, POSTUNIN, PREINST, PREUNINST etc.). Have a look at them. POSTINST is a post installation script. Copy it to your prefered location on disk and run.
Third method is to install rpm for ubuntu and install client binaries in regular way.

suggest upgrading to Networker 7.6 first and then 8.0 or 8.1  as 8.0 and 8.1 can support Ubuntu 10 and above.

For the installation steps, please check NetWorker 8 Installation Guide.

EMC will only officially support Networker 8.0 and above from next month.