Had a similar issue in adding "Start Command Prompt with Ruby" to context menu as it involves passing parameters along with the patch of cmd. Followed a similar procedure as the solution above
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\*\shell\Cmd With Ruby]
@="Cmd With Ruby"
"Icon"="C:\\Windows\\System32\\cmd.exe"
[HKEY_CLASSES_ROOT\*\shell\Cmd With Ruby\command]
@="\"C:\\Windows\\System32\\cmd.exe\" \"/E:ON /K
\"C:\\Ruby25-x64\\bin\\setrbvars.cmd\"\" \"--cd=%1\"\""
[HKEY_CLASSES_ROOT\Directory\shell\bash]
@="Cmd With Ruby"
"Icon"="C:\\Windows\\System32\\cmd.exe"
[HKEY_CLASSES_ROOT\Directory\shell\bash\command]
@="\"C:\\Windows\\System32\\cmd.exe\" \"/E:ON /K
\"C:\\Ruby25-x64\\bin\\setrbvars.cmd\"\" \"--cd=%1\"\""
[HKEY_CLASSES_ROOT\Directory\Background\shell\bash]
@="Cmd With Ruby"
"Icon"="C:\\Windows\\System32\\cmd.exe"
[HKEY_CLASSES_ROOT\Directory\Background\shell\bash\command]
@="\"C:\\Windows\\System32\\cmd.exe\" \"/E:ON /K
\"C:\\Ruby25-x64\\bin\\setrbvars.cmd\"\" \"--cd=%v.\"\""