HC08 devices are programmed by Monitor Mode via the MON08 debug port.

The following pins are typically required for incircuit programming with the Cyclones
VDD
GND
OSC
RST
IRQ
COM (usually PTA0)

You can disconnect OSC if there is a ~4.9 MHz or ~9.8 MHz external oscillator on the device. If you use the on chip 32.768 KHz clock, then OSC is required since this frequency is too slow for the Cyclone and a faster clock signal will need to be generated.

There are several port pins that control clock division to configure the baud rate. For example, they are PTA7, PTC0, PTC1, and PTC3 on the GP32. It will vary with each device. These port pins can be connected to the Cyclone or pulled up/pulled down directly on microcontroller for a smaller port footprint. The Cyclone Pro manual attached below has a description of the pinout and what port pins are required for each HC08 device family.

In addition, high voltage (> 8V) is required to enter Monitor Mode on devices that have already been programmed with a reset vector.