I built my house & did all the radient heating and everything by myself. It is pretty straightforeward, especially if yo do some backgound research. You can save $$$$$ doing it yourself, even if you don't want to do the boiler & etc. like I did.
With respect to earlier comments, it does take time to heat up a slab so if you want to save money with a setback it doesn't work, unless you are thinking of going away for a few days (then you'll need a while to get back up to temperature). On the other hand, most of what I read said it is more efficient because you don't need a high thermostat setting to be comfortable since its usually your feet that get cold first - much more of a problem with forced air than radient.
Basically the first thing to do is plan it all out. Depending on where you are, the size of the house, number of zones and so on, it can get pretty complex (lots o loops). But with a small house, you can get away wth one or two. In fact my mainfloor & basement are 8000 sq feet and I got by the first winter heating the basement zone only ('twa a mild winter).
Make sure your slab is on top of min 2" styrofoam insulation on top of gravel. There must be poly between the concrete and styrofoam or it'll crack like crazy. Use 6" steel mesh reinforcing and use this to fasten the PEX pipes to with tie wraps. Pex is usually 6" on center around the perimeter, then 12" OC elsewhere.
There is a good layman's book on the subject I can find if you want. Also, I can walk you through the entire process step by step, but that would be best done off line. Its not that hard after all - I ain't that bright & I got it to work the first time.
