Can be done, but I do not know if that will make you happy.
First you have to assign the "+" to a key and the "-" to a key on "Other..." tab in the MIDI2LR options.
Next you can use the left mouse key in the MIDI2LR server to assign "Keyboard Shortcuts for User -> Key ??" to a pad.
Now comes the difficult part, in the develop module open the basic panel and click with your mouse on the word "Exposure" to use the pads,
you can jump to "temperature" using the "." or "," key or by clicking on the word "temperature".