Setting up userconfig file
Using a custom userconfig file is a way of keeping things nice and neat so you can make easy changes to any command variable. Anytime the game starts, this file gets executed and overrides any commands that may be in the config.cfg file. The userconfig used to be named autoexec before the days of Steam. Autoexec may still work but we are going to use userconfig for now.
Locating the file
First we need to find your userconfig.cfg file. It is usually found in the "valve" folder of your Half-Life installation. It also can be found in a mod's folder, e.g.: "ag", "svencoop" and others. If it is not there you can easily create it manually.
Editing the file
Open it up using a text editor such as Notepad. Now you can just throw scripts or commands inside of it. See Half-Life Scripts for a nice list of scripts used in Half-Life speedrunning.
You might want to have a description of each script, so you know what each script does when you edit the file again or when you want to change something. Use // before a script to make the line "commented" and it will be ignored by the Half-Life engine.