The problem, as I understand it, is that PureConnect only ever connects as a single user (ICAdmin) who, in turn, requires "Supreme Being" like rights to the whole e-mail system.
With regular GMail, there is no way for that to happen.
Now, with Enterprise / Business GMail, it's not hard to set up. If it's just for testing, then (I believe) you can have up to about 5 mailboxes free of charge, which would allow you to set up ICAdmin and one or two other mailboxes for users / Attendant / Whatever you want to test...
Alternatively, you can spin up a VM (Linux or Windoze) and install a generic IMAP / SMTP email server on it (there are plenty around that are Open Source / Free) and use that. This is how we have it set up for the Lab environments we use in training.
HTH