AFAIK KMVX is meant to be used when km resides on a writeable removable medium like a USB stick or a Zip/Jaz disk. In such a case you would never set km as the default browser. Since you've done that, I guess you've installed km on your hard drive and just want to have your profile in the km directory? You don't need any additional tools for that! Place a profile.ini (text file) in the km root folder:
[profile]
path=Profiles
IsRelative=1
An empty profile.ini has the same effect.
path specifies the path to the folder which contains your profile(s). If
IsRelative is set to 1,
path is taken relative to the km root folder. Otherwise
path must be a fully qualified path.
@guenter: AFAIK KMVX.exe is meant to run k-meleon.exe. So, it can't replace k-meleon.exe. Or am I wrong?