USALS is a calculated aiming program that works with USALS HH motors to automatically aim a calibrated dish/motor at the selected satellite. Typically it is used for KU band motors. It does not work with DiSEqC 1.2 based controllers.
There are a few KU motor install guides on this site that provide the steps for installing and programming a USALS dish. Basically, activate USALS in the receiver, Input the longitude/latitude for the install location. Assemble the dish and install on a USALS HH motor. Set the dish elevation, motor elevation and roughly aim for true South. Connect the coax, power on the STB, program the first satellite and select an active transponder. The motor will drive to the calculated satellite position. Adjust the motor azimuth to lock and optimize the signal quality.