The installation guide has been on that site for months.
There are a few reasons why it hasn't been a contact details-esque section on the 3DS capture website:
Here's my predicament: I have plenty of boards now. I'm hesitant to start taking orders because of the aforementioned noise problem. I've been aware of it for a while; I hoped I'd find a better solution or be able to brush it off, but no dice; I think it's bad enough that most people won't be willing to live with it. I ordered a bunch of those ground loop isolators off of ebay, but it could take a couple of weeks before they're here. I could pick some up from the local Radio Shack instead, but that's like $25 instead of $5.50, so screw that. Another problem (really just my problem not yours, unless you're installing yourself) is that the screws I got for the case weren't very good, so installations are a pain. Screws are slightly too wide so they get jammed and strip easily. I'm getting custom screws made but that will also take a couple of weeks (order was placed a while ago, but these things take time).
I haven't updated the website yet because I'm afraid it'll get damn awkward explaining this stuff. Official price will be $200+shipping installed or $170+shipping if you're doing it yourself. So, uh... I'm not sure where to take things at this point. I'll sell you a board if you want, just so long as you're aware of the concerns mentioned.
I also need to mention that the price does not include custom clearance which costed me an extra £35 (~$65).
Oh if delivery doesn't screw up I am getting my modded 3DS
tomorrow.