Yes, F would be 0 to 255. I think S of 251 is optional. I'd try a known code like Power (F = 8) first to make sure you're on the right track. You can skip the posted codes (convert from hex to dec) to save some effort if you want.

If you find anything new, please post your results.

Here are some discrete codes (in decimal) you can also skip:
90 DSCRT AV1
208 DSCRT AV2
191 DSCRT COMP1
212 DSCRT COMP2
206 DSCRT HDMI1
204 DSCRT HDMI2
233 DSCRT HDMI3
218 DSCRT HDMI4
197 DSCRT OFF
196 DSCRT ON
119 DSCRT RATIO 16:9
118 DSCRT RATIO 4:3
175 DSCRT RATIO ZOOM
213 DSCRT RGB-PC
214 DSCRT TV