I think I have found the answer to my own question - I will describe it here in case it is useful to others. There are two possible solutions. In either case, you must create a context variable called params_file in your job (note that the name params_file is arbitrarily chosen).
One solution is to use a tContextLoad in each job. Place a tFileInputDelimited component that reads from the named in context.params_file, then connect it to a tContextLoad component.
An easier solution is to use the Implicit Context Load option in the job settings or project. To do this, go to the job properties view when you have the job open, and click the "Extra" tab. Check the "Implicit tContextLoad" option, and choose "From File". Then in the file path, you can enter context.params_file.
If you want to load the same context for many jobs, you can use the Project Settings to set the implicit context load settings jobs. To do this, go to File -> Edit Project Properties, and Choose Job Settings -> Implicit Context Load. Configure the settings here as above. Then, go to the Job Settings -> Use Project Settings and select all the jobs that you want to have these settings. When you click OK or Apply, the settings will be applied to all of the jobs.
This appears to work for me. Anyone should free to correct me if I am mistaken on any point.