There is no available app note for the S12XD family (but watch this space).
However, the app note for the S12D family will take you fairly close and
AN2615 describes the key differences between the families.
AN2727 covers the S12D in some detail. Notable hardware differences would be:
1/ Oscillator type is Pierce only (two types) on the S12XD
2/ The Reset and Test pins have pulls on the S12XD
3/ Expanded bus is completely redesigned on S12XD
4/ PLL component choice is slightly different - there's a PLL Calculator for this
5/ Pinout will be slightly different - use the S12XD Data sheet
The general guidance around power supplies and minimising power consumption all apply.
