I did a contract using M68HCS08 a while back, IIRC device was MC9S08QG8.
For development we used CodeWarrior with PE micro universal multilink interface (part# on device is: USB-ML-UNIVERSAL).
But if all you want to do is load the code, the BDC interface is fairly well documented under "Development Support".
As part of the manufacturing test system, I implemented the BKGD 1-wire interface by "bit bashing" it on an STM32F103 (Blue Pill) for the purpose of loading firmware, and it worked quite well.
(and much simpler and easier to automate than trying to do it through CodeWarrior and PE interface which of course "needs a windows-PC").
Dave