try put them into Settings -> Devices/Algorithms -> select your card -> select Equigash (excavator) -> and type them into field Extra Launc Parameters
I'm trying but it doesn't seem to work
You are right, I got the same issue, and after checking with process explorer there is no extra params.
I got a look on Nicehash's GUI on github https://github.com/nicehash/NiceHashMiner/blob/master/NiceHashMiner/Miners/Parsing/ExtraLaunchParameters.cs#L175
It's only handle '-c1' and '-c2' options..
I'm opening an issue on github.