To use the PS/2 mouse on the FPGA side of the DE1-SoC, use files from the following website http://www-ug.eecg.utoronto.ca/desl/MSO_de1_tutorials.html at the University of Toronto.
Although only partial functionality was achieved in 2022, the mouse clicks and discrete up/down and left/right signals with no magnitude in the directions of movement is possible. This was possible using the "mouse_part2.zip" files, which includes two .v for the two necessary modules. Their lab manual (linked at the top of their webpage) goes into more detail about how the modules function.
Pin assignments are solved by including the PS/2 option when using SystemBuilder to generate the initial files for a project. To integrate the necessary pin assignments into an existing project, copy over the generated pin assignments into an existing .qsf file.
2022/06/08 Written Information by Derek Li