Timing multiple sections with ArrowVortex autosync
ArrowVortex autosync is pretty good, but it doesn't work with songs with multiple BPMs usually.
It is possible to work around this by selecting a single constant-bpm section of the song using Tab, and then using ArrowVortex's autosync with the section selected. ArrowVortex will output the calculated BPM considering only the selected section.
Note that using this technique requires you to be able to identify a discrete section with the same BPM. This may not work as nicely on live music or continuous BPM changes; at that point it is probably more effective to sync to each quarter beat manually.