I know that with webMan, you can set a a specific PSID & IDPS at boot time, but webMan only works on Cobra firmwares. If you upgrade to the latest Rebug, I think that has webMan integrated already as it's a Cobra enabled firmware.
I also think you can set a boot IDPS & PSID with ControlConsole?
You must login or register to view this content.
Never tried this function though, so I don't know if it works.
Anyhow, I know the struggle man. I hate having to set the CID at every boot. xD
Anyway, since PS3ita Manager works with Rebug firmware, you could use CFW setup which is also for PS3ita. It asks you if you want to set the target ID back to CEX as soon as you open it, so it'd be a little quicker than using the manager.