Channel Master went through an update not too long ago and they have not yet provided us with a permanent replacement coding. However, a custom remote had been created and posted on the JP1 Forums that will allow you to add a custom remote to the Slingbox. I've linked the Custom Bin File upload process article, as well as the Channel Master remote code download, below for ease of access. If you follow these steps, you will have a working virtual remote. Please keep in mind though; as this is a custom remote file, this may not look identical to your physical remote.
I hope this helps!
Sling Media Technical Support