We added a recirculation pump about 6 months ago and while the HW is not "instant" it is many times faster to all faucets. I bought the pump at Lowes (around $200) and installed it myself since plastic pipe is easy to work with and there was an electrical outlet near the HWH but there are "handymen" around who will do it or you can pay a plumber. You also need to install a small "mixer" under the furthest sink from the HWH. The only other way is to run another line (return line) from HWH to furthest sink which is pretty much impossible around here. The only downside is when you turn on the COLD water you get a couple seconds of WARM water through the cold side.
This kind of explains how it works:
Quicker Hot Water With a Hot Water Recirculating System