Many Eclipse algorithms have the LFO already working like this.
You'll see Retrigger and Angle parameters
Retrig = Whenever the sweep rate is changed (either manually or by updating the tempo), the new rate is crossfaded
with the old rate. The value of Retrig controls how long the crossfade is as a percentage of the old rate. Thus, a
value of 1 cycle means that the crossfade will be complete in one cycle of the old rate.
Angle = given most configurations of the Eclipse, the sweep rate will "start over" when the tempo button is tapped or
when an external sequence is started. Angle determines where in its waveform the sweep begins.
MIDI is already connected to the LFO rate. By setting T_Rate to any rhythmic value and choosing Eclipse tempo source to MIDI, MIDI Clock does the work. Or you can use any CC message to tap tempo.
Is this what you are looking for?