Once you have uncompressed the distributed tar file installation is completed by telling Matlab where to find the source code and documentation. Start up Matlab and use the "Set Path..." option from the File menu to open the path setting dialogue. Use the "Add Folder..." button to open a file browser, navigate the msat subdirectory, select it and choose "open". This adds the MSAT functions and documentation to your path. Choose "Save" to make this change permanent.
Once MSAT has been installed documentation on all functions can be found by typing "help MS_funcname" at the Matlab command prompt. Further documentation can be found using the Matlab help browser and clicking on the MSAT Toolbox section of the contents page or online, from this website.