If you need to be "in application" programming an RS08 then you probably need to re-visit the selection process. The programming is similar to the S08 but the main problem is you need to supply your own programming voltage. This then uses up one of the few pins that you have and you need to switch it.
Not to mention the small amount of RAM and FLASH you have to burn up with bootloaders and programming code.
There is only one reason to select the crippled RS08 over the S08 and that is to save 50c. If you spend most of the 50c making up for its shortcomings you have selected the wrong device. There will always be exceptions to statements like this, but this also explains the lack of information about it too.
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