You might want to look at
https://www.mobileread.com/forums/sh...d.php?t=247678 to get some ideas about how to create a custom KoboRoot file that would allow you to easily get an updated wpa_supplicsnt.conf and certificate onto your device.
The zip file in that post just contains a KoboRoot.tgz that replaces /etc/wpa_supplicsnt.conf. You would need to customize the wpa_supplicant and also add in the cert file in an appropiate directory.