As far as i know there is no possibility to access the certificate store on Windows Phone8 devices.
But i found out how to see all installed certificates. This can be very helpful for troubleshooting because Windows Phone8 doesnt show many error messages.
- access the setting WIFI
- select a wpa2 enterprise WiFi
- enable “Validate server certificate”
- Choose a certificate
This workaround is a bit circumstantial, but as far as i know the only way to check installed certificates.
Windows Phone Version: 8.0.10211.204