I'm the author of Mac Kung Fu, and recently stumbled on the following iPhone tip. Create a new email and then, in the body of the mail, click the create link button. In the address field, type any of the links at the bottom of this page. For example, to create a link that'll instantly switch the user to the VPN configuration page of Settings, type:
The catch is that you'll need to use a mail client that doesn't check for the 'http' component in a link. Mail on OS X does this, so can't be used, but Gmail's website works fine.
Send the mail to the friend/colleague you're trying to help, then when they open it on their iPhone/iPad, all they need do is tap the link to switch to that preferences pane.
This technique is adapted from a tip describing how to use the IconProject app to add pref pane links to a user's home screen. However, Apple will likely remove the app when they learn it has this secret power.
It's not possible to create a webclip file and email it to the phone. When an attached webclip file is tapped, Mail simply says 'Mail cannot open this attachment.' Presumably this is for security reasons.
It's possible to edit an iPhone backup file using iBackupBot to swap-out the URL of an existing home screen web link for a preference pane link, but this is complicated and a little risky. However, doing so would allow home screen shortcuts to preference pane links even on locked iOS devices.
[crarko adds: I haven't tried this, although I can certainly see the utility of the hint. Obviously it's smart to verify the source of an e-mail before clicking on some arbitrary link contained within.]