I didn't have any problem running the TFPT cmdlets on Win 7 x64, so I initially didn't understand the .reg file and all of the 64-bit checking. Michael reminded me that there's a 64-bit PowerShell console!
The TFPT PowerShell CmdLets since the first 2008 version only run under 32-bit PowerShell. If you explicitly execute the 64-bit posh, which is what you're likely not doing, you will get an error when trying to import the modules from the DLL. It's been well documented, but I just hadn't put a link in the comments (here's the one for 2008, one of them for 2010, and the one for 2012). I use ConEmu for my console and explicitly specify the 64-bit posh executable when starting a posh tab. The registry entry allows the cmdlets to be imported under 64-bit. There might be a better way, but at the time I found the registry entry and that worked for us.
So, it seems that we have a solution (run the .reg file). But, I don't think that's what the Register-TfptCmdlets function is doing. It's just testing for 64-bit Windows, not a 64-bit session. Let's straighten that out and get the README dressed up to talk about making this call.
We do want the user to be responsible for all of this in their session (via the profile), right? Because this module just uses these tools, it doesn't prescribe how/when to set them up.