[The_Nimaj]

Getting to and using FX Mode

First enable/add the line FADER_CONTROLS_FX=1 to your ini file.
You don't have to restart reaper either, press SHIFT+STOP+PLAY (shift latch doesn't matter here) if it worked, the three lights will flash. (This button combination reloads the ini file, updated your button mappings)

Then, press SHIFT (and hold, if shift latch isn't enabled) + BANK. The BANK button will begin to blink and if you currently have a track selected with TrackFX, the fader should jump to the value of the first plugin's first param. If there are no FX on the track (or on the last selected track) the Bank light will blink quickly a few times before shutting off. This means that FX mode failed.

NOTE: In some rare cases, entering FX mode on a new track or one with newly added FX will fail. Simply click off of the track and selected it again. This should fix the issue.

You can use the PAN knob to select different params within the plugin and use the Channel Select to select the next or previous plugin in the chain. For now, the info tooltip in the bottom left hand corner of the REAPER window will briefly display the currently selected FX or param. The fader should also jump to the value of each selected param! This will allow you to automate FX params like the volume, but there are bound to be some bugs with this feature.

Simply Press the BANK button once more to exit FX mode.