There isn't a list that's laid out for us, however there's a widget that you can query on this web page (http://support.slingbox.com/get/KB-5000164).
Also, Alan Richey is able to create remote update bins for most devices which are listed in the Logitech Harmony Database (http://www.logitech.com/harmony/components).
Actually the device 'type' you select is not something that Sling can change, it is really defined by the UEI IR chip they use, and the associated software used to add the remote codes to the Slingbox. DVD/VCR is just not recognised as a valid type.
If it is supported your box will appear as a DVD. And as eferz said, if it isn't supported I might be able to build a remote. But first, check out this thread: https://community.sling.com/thread/3300?tstart=0