Have a look at the Libreswan Wiki. Both their IKEv2 examples use certificates, but you may be able to get it going with PSK's. The ClearOS CA and user certificates are probably not usable because of the specific X509 extensions required by some clients. Anyway, for Libreswan the certificates get stored in a completely different place.

Thanks Nick,

Do you have instructions you can share for manually setting this up.

OpenVPN requires we install an app on every computer and mobile device. I am not looking forward to supporting that..

I am fairly certain that, despite its claims, it can't as it is missing one key configuration parameter. Libreswan can be configured by hand to do it. The sensible alternative is OpenVPN; the not so sensible one (for security concerns) is PPTP.