Towards the top of my script there is this line:

set @LoginName = 'LOGIN_NAME_HERE'

Set the server level login name associated with one of your users here, and run the script. Then set @LoginName to the login name of your other user, and run the script again. This will accomplish what you want. I'm assuming these two users and the 253 databases are on the same server. If they are on more than one server, just repeat the process on each server.