SOLVED: Metronome question

Is there a quick, easy way to set the metronome tempo by measuring between, for example, kick drum hits of an existing song? I'm in need of a long count-off for a bass player to re-record an intro, but at a slightly slower pace than when the band kicks in. I don't know if there's a way I can approximate the tempo based on the ruler or some other means. Thanks! 

Solution: Use Project => Insert Tempo Change.
Or, as Karl points out a clever way: Use a MIDI track, and tap along with the original beat of the band or drummer's kick. 

To see how these are done, I highly recommend the SWA vids.

Sent this to Feature Request for Sonar X2:

"In a pre-recorded band's tracks, I'd love to grab a ruler tool, zoom into a track, and "measure" (click-drag) between, say two kick drum beats and see what the tempo is. This would be great for setting a metronome for a new count off, or to replace an existing part using a metronome. Maybe even allow Audio-snap to map out the tempo map for a song as well, perhaps. This would be great for a drummer that needs to re-track his drums to a song that was recorded without a click/metronome."