isp chip
I don't understand your question. What do you mean by "triggering the test board"?
After an UART-ISP chip has been programmed, you can disconnect the serial connections. To enter the programming mode again, different chips use different methods, read the datasheet of your particular chip.
You can also roll out your own bootloader, which might then be independent on UART; nevertheless this is not an easy task for a novice.
The "dongle" you mention appears to me to be intended for some other type of microcontroller, with SPI-like ISP (such as the PICs, AVRs and AT89Sxxx series).
wek
PS. For '51 specific question better come to the 8052.com 's forum.