You can use the Classlist Editor's Add tab to add an account. It will be created with low permission level, and so then you can use the Classlist Editor's Edit tab to change the person's permission level to admin.
If you do this in the admin course, then these users will be added to future courses as either admin or professor (I forget which). For the 4 existing courses, you'd have to go into each one at this point and add them if you want them there.
WeBWorK Main Forum
Adding another webwork admin?
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