There isn't a way to script the adding of accounts. However, all the account details are held in the ini file of the POP Collector program folder, so it would be possible to generate the ini file. I haven't documented the file at all, but it is plain text except for the passwords (which are very basically encrypted). The best way to see the format would be to enter a couple of test accounts with dummy values, and then see how the ini file looks. You could then script the creation of the ini file using the same format.
POP Collector only reads the ini file on start-up, and writes to it on close so any changes need to be made without PC running. Hope this is enough info for you. If not, I could document the ini file, but it won't be that soon.