The process for adding audio editors is described here https://www.cakewalk.com/Support/Knowledge-Base/2007013099/Adding-third-party-audio-editing-software-to-SONARs-Tools-menu
 
Noel went into more detail here http://forum.cakewalk.com/FindPost/1850413
 
Based on these links I created a new utility program, SONARToolsEditor (this link still works for the old SONAR version but users of 64bit SONAR or CbB should use the newest version). The most recent direct link is here. Rather than using direct links a better source is here, a page containing the links to the current versions of everything.
Old SONAR info:
Most only need SONARToolsEditor.exe. It should work on 64bit Vista and newer maintaining the tools section of the Utilities menu for both 32 and 64bit SONAR running on 64bit Windows. SONARToolsEditor32.exe is intended for 32bit Windows only.
 
Edit1: v2.1 updated to new version. Now has command line arguments to override drop down defaults. It is packaged as a zip, including both 32 and 64bit versions and a Readme.pdf
 
Edit2: v2.3 minor UI reformatting
 
Edit3: all software updated for CbB. A new tools editor was created. The initial release of the new editor is v1.1.

Woohoo! Another useful tool added to the growing collection. Thanks scook.

Scook, thanks for this . . . looks like a helpful tool, I've downloaded and will have a closer look, much appreciation here for all your efforts on this forum.

Awesome!

Thank you, scook!

On a side note, I've done this the manual way and I've noticed that RX3 always opens with the last used file instead of the region I'm sending. Trying it a second time I do get the correct region. If I close the file in RX3 before closing RX3 proper, it also works fine the next time. Did I do something wrong in the settings or is this just a bug or expected behavior?

That's an RX setting, where it re-loads the previous thing you worked on. Have a look through the preferences in RX; I can't remember what it's called, but you can switch it off.

Thanks for the contribution, Scook. It's a nice little tool. It works good, too. I used it to successfully add a wave editor to X3. I prefer a tool like this rather than having to go edit the registry manually.
 
Cheers! And thanks for your work.

I would mark your post Helpful if I could  :)
 
Thanks Steve

John T
That's an RX setting, where it re-loads the previous thing you worked on. Have a look through the preferences in RX; I can't remember what it's called, but you can switch it off.

Thanks, I looked and it's in the preferences under "misc", and called "Resume last editing session when app starts". I turned it off. Still seems strange to me that it would ignore a file it was handed, regardless of that setting. But this hopefully fixes it!