I found this gem in the code when trying to solve the same problem as Halogen.
Line 428 in system/expressionengine/libraries/core.php
/* Hidden Configuration Variable
/* - use_mobile_control_panel => Automatically use mobile cp theme when accessed with a mobile device? (y/n)
Go to the Config File Editor in the control panel, scroll to the bottom and add a new config variable.
Enter use_mobile_control _panel into the first box then n in the next box, then Update.
It applies to all mobile devices so not ideal, but if an iPad is your main mobile use then it’s worth it.
The whole issue of re-directing mobiles to another stylesheet or page is going to get big.
The iPad is not really a mobile and is more than capable of displaying a standard page, but some iPad formatted pages are an improvement, but we must be able to choose.
I’m now starting to think about the different methods for how to code my sites to allow the choice but initially re-direct to a mobile stylesheet.