I dont know any link for a tutorial specific for sherwood syscons (the syscons with pins all around) but in short... are this steps:
1) Install python v2.7 (as far i remember the python script that you need to run later was updated to work on python 3.x too, but i would install v2.7 just incase)
2) Download the python script named ps3_syscon_uart_script.py from this link
https://github.com/db260179/ps3syscon
3) Go to the "device manager" in windows with the USB-to-UART adapter connected to ther PC... and search for it to find his port name... lets say is named COM3
4) Open a terminal window and type "ps3_syscon_uart_script.py COM3 SW"... this should authenticate you with your syscon SW located at port COM3
If everything went fine you can run the commands that appears in this lists
https://www.psdevwiki.com/ps3/Syscon_Firmware#Command_list
Keep in mind some of the commands in mullion (the syscons
without pins all around) was removed in sherwoord (the syscons
with pins all around), and some others are locked
To show the errors you need to type "errlog"... and to delete them type "clearerrlog" (or ERRLOG CLEAR in uppercase)
*You can also make a dump of all the accesible areas by running the other script in github named SysconEEPdumpSW.py