BB Tour 9630 :: Stop Device Checking For Wireless Updates?

I'm trying to support nearly 100 Blackberries (mostly the Tour), and any wireless update breaks the phones with various results: anywhere from just deleting the email sync settings (all carriers) all the way to the phone unable to make/receive calls (just T-Mobile for the lack of calling, Verizon or AT&T seem unaffected thus far). We do *not* use a BES server, however, if that's what is needed, I'm certainly willing to go there. If and when an update is needed (by our standards), I will perform them. I really don't want anything coming from Blackberry, ever. I instruct users to hide the update icon, however, they always say it eventually comes back and keeps prompting to install the update. To rid themselves of the annoyance, they do the update, break the phone, then have the greater annoyance of waiting until I can get the phone fixed.