Right now the only reason I haven't bought LFO tool is because Logic X requires ridiculous workarounds to route MIDI to an AU. I was thinking though, there IS support to route audio via sidechain into an AU. Is there a possibility that there will be an LFO Tool update which can use an audio sidechain to trigger the effect (almost like a gate)?
In case you're doing it in a more convoluted way:
New instrument track, add LFOTool as an AU MIDI Controlled effect, set the audio source via sidechain.
It's easier in other hosts, for sure.
Audio to MIDI would require extra audio inputs, and is not sample-accurate like MIDI..TBH this means isn't very likely, but I certainly won't rule it out.
just for the protocol:
audio trigger sc for LFO tool would be lovely