lpoptions -p printername -l
Prints PPD options, "Default" is filtered from option name (similar to looking at the raw PPD)
It uses a colon when reporting key value pairs; replace that with an equals sign when specifying an option
The option name stops at the first slash
Example: The duplex option for HP printers will output like this "HPOption_Duplexer/Duplex Unit: *True False"
When specified as a "-o" option it would be "HPOption_Duplexer=True"