Download the zip file and unpack the directory _PERSONAL and the files it contains to:
%USERPROFILE%\My Documents\LTspiceXVII\lib\sym\
Unfortunately, github adds a directory named "LTSpice-master" to the zip file.
The "_PERSONAL" directory is required because there are references to: "../sym/_PERSONAL/" in the .ASY files.
Files in the _STANDARD directory can be used to replace the components in:
%USERPROFILE%\My Documents\LTspiceXVII\lib\cmp\
standard.bjt (1592 models)
standard.dio (2028 models)
standard.jft (1074 models)
standard.mos (1632 models)
The files in the _CUSTOM_SYMBOLS directory can be used instead of the originals (without _HP in the filename).
I got irritated because I have to mirror and rotate 90 degrees twice, every time I use the PNP or PMOS symbols.
Also RES and POLCAP have replacements that are drawn as European symbols.
Better do NOT replace the originals in the sym directory. Keep in mind that the original files will be overwritten at the next LTSpice update. For that reason I added the _HP in the name.
In case you have trouble using these parts, please don't hesitate to create an "issue". I really appreciate to receive feedback from other LTSpice users.