http://das.nasophon.de/klick/he parameter -t enables listening to JACK transport, and -T makes klick the
transport master.
You can also use the parameter -j (instead of specifying any tempo or
meter). That way, klick will simply play along with any timing info it gets
from the JACK transport master.
Both ways should work fine in conjunction with Ardour.
Handy when you want to use an metronome on the 2nd and 4th beat, without having the loud first beat, together with Ardour.