I'll volunteer for the job!
Tony's Train Exchange has a very good reputation. This forum's David Bedard seems pretty knowledgeable as well.
I'm sure there are others, but those are a couple that come to mind.
Rotor
Jake: How often does the train go by? Elwood: So often you won't even notice ...
http://www.dcctrain.com/shop/custom.asp?recid=2
Dave
Lackawanna Route of the Phoebe Snow
Litchfield Station in Glendale, Arizona, installs decoders. You don't indicate where you are, but he or Tony's Train Exchange in Vermont would be one of my first choices.
http://www.Mr-DCC.com
You might want to visit a local model rail road club in your area. There is always some one doing decpder insals for the club. I have been doing most of my clubs decoder instals for a couple of years now. The plus side of local instals is no shipping.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
USAF (Retired)
My LHS, www.mainetrains.com, does electronic installations. You should look for an LHS in your area, and see if they do them, to save on the expense and risks of shipping.
Consider sound while you're at it. I'm afraid you're going to find that having this done is kind of pricey, and you might want to get sound installed the first time around rather than have to do this all over again later.
It takes an iron man to play with a toy iron horse.
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum
While I respect the online suppliers listed who do installations, you have to consider that the shipping both ways may cost nearly as much as the decoder. Add this to their installation fee and it becomes rather expensive. I'd look for an LHS in your area that does the work.
But I'd bet with a little practice you could become comfortable with doing your own installations. It's only a matter of soldering 4 - 7 wires. And if you went with M1 decoders, the TCS "good proof" warranty would assure that messing up wouldn't cost you anything.
Are these new engines or very old ones or?? Most new engines - made in the last 5 years or so at least - have "plug and play" decoder receptacles. You take the body shell off the engine (or tender if a steam engine), remove the eight pin 'dummy plug' and plug in a decoder and put the body back on. That's it.
It's easy to be intimidated but if you're going to continue modelling for...well, the rest of your life, do you really want to be dependent on someone else to do this for you - especially when you can become an expert at it within a short time??