The idea is to assign the EFC under one setup code, then switch to the other. Any such keymoves should stick after you change setup codes, as 3FG described. If shift-Power doesn't work for you, put it on some other button.
If he follows this thread, I'm sure he'll share those docs as well. I don't know where they are. Here are the EFCs for 30842 that I got from a SR702 user (prepend 00 to each):
180 input - MultiChannel 060 input - DVD 108 menu 104 display 100 return 107 setup 040 dsp - surround 103 dsp - all stereo 038 dsp - thx 036 dsp - stereo 115 dsp - pure audio 249 dsp backward 245 dsp forward 164 channel select 171 level down 167 level up 114 late night 110 Re-EQ 170 discreteOff
and for 30135:
058 input - Video1 054 input - Video2 056 input - Video3 002 input - Video4 057 input - CD 053 input - Tape 059 input - Tuner 055 input - Phono 183 vol up 187 vol down 184 mute 181 channel up 185 channel down 128 dimmer 232 sleep 191 up arrow 195 down arrow 188 left arrow 192 right arrow 130 enter 131 index backward 124 index forward 247 rewind 249 fast forward 120 play 118 pause 123 stop 245 record 164 dsp - direct 255 test tone 180 discreteOn 044 zone2 [prefix]