Specifically, I want to be able to see what sample rate each is set for (and perhaps to alter that) before I start it up in stand-alone mode. The reason is that I am using a Roland UA-22 USB interface, which seems to lock-up if an app tries to use a sample rate other than the one the UA-22 is physically set at.
 
The synths give a message saying something to the effect that the new sample rate has been stored in the registry, but I cannot find any likely looking reg key.
 
I am using 64-bit Windows 8.1 Pro.
 

There are stored in synth specific entries under HKEY_CURRENT_USER\Software\Cakewalk Music Software\microHost in the key SampleRate. The SampleRate values are stored as dword values so 44100 is 0000ac44

Thanks. That's interesting. I'd looked there, but in my case the SampleRate keys are not present for any of the three synths. I'll force them in at 48000 and see what happens. I'll report back later!

Excellent, Scook! I added the three keys and the synths now work as expected. Slightly oddly, in each case the synth returned a "sample rate changed - adding settings to registry" the first time I accessed the Roland latency control panel - odd, only because I hadn't actually changed the sample rate. Inspection via regedit didn't appear to show any actual change to the keys that I had manually created. Anyway, it's working, so thanks again!
 
Pushing my luck and imposing further on your generosity, I don't suppose you know how to do a similar trick to IK Multimedia SampleTank and its family? There is a config file for each, but it's encoded apparently.
 

Don't have any IK synths, sorry.

Specifically, I want to be able to see what sample rate each is set for (and perhaps to alter that) before I start it up in stand-alone mode.

 
It may be a little easier to access from the microhosts themselves.  The microhosts detect the supported sample rates of the audio driver upon launch, and reset the sample rate to an available one when it detects an unsupported rate.  With the microhosts open:
 
 F3: Set to 44100
 F4: Set to 48000
 Shift+F3: Set to 88200
 Shift+F4: Set to 96000

B Rock - Thanks. That's very interesting to know, but (in this case) I think the problem was that changing sample rate after instantiation was freaking out the Roland driver. I spent the best part of two days with the assistance of two very helpful Roland support guys trying to get this to work, and in the end I thought that "protecting" the driver from the behaviour it didn't like was the pragmatic way forward. The registry hack seems to have solved the problem, and I don't plan to deviate from 48k, so I'm hoping it stays that way.
 
I'm curious to know why the registry keys had not been written by the microhost (despite the message to say that they had been), but this is only intellectual curiosity, of course.