Hi,
You should be able to run the BDM, no matter which baud rate you have set up for the SCI or which external clock you are using.
I have no experience with the 9S08SH8, but as the SCI module is the same is all other 9S08s, this should to the trick.
If you have an 8 MHz bus clock and want to run the SCI at 19.2 kBaud, the SCI receiver must run 16 times faster, or 16 * 19.2 Kb = 307.2 kHz.
If you divide 8 MHz/307.2 kHz = 26.04.
So set the
SCIBD = 26;
and it ought to do the trick.
Regards,
Ake