I have added notepad++.exe to my Path in Environment variables.
Now in command prompt, notepad++.exe filename.txt opens the filename
To define a console alias, use Doskey.exe to create a macro, or use the AddConsoleAlias function.
doskey test=cd \a_very_long_path\test
To also pass parameters add $* at the end: doskey short=longname $*
AddConsoleAlias( TEXT("test"),
TEXT("cd \\\\test"),
TEXT("cmd.exe"));
More information here Console Aliases, Doskey, Parameters