I think it is not that easy, but it is possible.
I enter sudo mode and cd to /usr/sbin
I rename the screencapure programm :
mv screencapture capturescreen
And after that, I create a symlink to the old one:
ln -s capturescreen screencapture
now when calling capturescreen, It is called capturescreen.
But when doing CMD+Shift+3, I get the screencapture process.
But You could fix that with creating a Service in Automator and create a Shell-Script-Action, simply calling "capturescreen ~/Desktop/Output.png"
And after that in the System-Preferences, Assign a Shortcut to the Service.
But you could also simply call Terminal and enter "capturescreen ~/Desktop/Output.png"
Even further, you can modify the screencapture action in automator to get the timestamp back and use it as the main tool for schooting screenshots.