Possible to manually edit arguments?

[Selur]

Last I checked 2pass crf was abandoned (Hybrid did support it while the x264 devs did too) and 2pass cq doesn't make any sense, since cq always uses a constant quantizer.
You can add command line additions under 'x264->Misc->Imports/Additions->Command line->Addition', in x264 the last mention of an option overwrite existing ones.

which (according to documentation and attestation)

I would like some reference to any documentation regarding this from the x264 team, since like I wrote before 2pass cq doesn't make sense and 2pass crf was abandoned.

Cu Selur