I'm planning to install XP on a laptop that came with Windows 8 to have a dual boot.
Is it possible and safe to do a similar procedure as the one described in "Installing Windows XP after Windows Vista or Windows 7" but for Windows 8 ?
Doubtful. As most newer machine comes with UEFI which is required by Microsoft. It is not compatible with Windows XP. Best thing you can do is try. But remember, being such a new machine, the likelyhood that you will have drivers to actually run the hardware within XP is slim to none.
If you have a non-UEFI machine, yes, you may. If you have a UEFI machine, you'll have to disable UEFI in the BIOS and reinstall Windows 8 from scratch to dual-boot with XP. In this case, I recommend using a virtual machine instead.