The LFO already is synced to tempo/bpm… It-Alien even said so in his reply.
If you are working at speed 6 and every beat is equal to 4 pattern rows, then you can set your LFO frequency to 4 LPC and it will cycle once on every beat. Now if you change BPM in your song, the LFO will stay synced to the new BPM and will always cycle once per beat.
If you want to trigger the LFO from a different position/phase (so that it starts out rising or falling, for example), then you simply put an x6yy command into the pattern, where x is the number of the LFO device in the DSP chain, and yy is the position/phase you want ranging from 00 to FF.
Here is another thread dealing with LFO stuff.
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Unless you mean something totally different and I’m totally missing the point?