Is there any keyboard short cut to input mac key symbols like shift, cmd, ctrl
EDIT: I found another way to do this, and is much easier and less complicated.
Go to the Language and Text preference pane and select the Text section.

From there, you can substitute typed-in text with the symbols that you want. For example, I set commandkey to be replaced with ⌘. This makes it much easier to type in the symbols. 



No, you do not need to.

Go to System Preferences, and open the Language and Text Preference Pane. Select Input Sources, and select Unicode Hex Input:

After doing this, select Unicode Hex Input as your language input (as shown below), and you can enter the characters using the unicode hex of the character, by holding ⌥+ABCD, where ABCD is the unicode hex.


The unicode hexes are (the ones you requested and a few others):


Shift Key (⇧) - 21E7
Command Key (⌘) - 2318
Control Key (⌃) - 2303
Option Key (⌥) - 2325
Backward Delete (⌫) - 232B
Caps Lock (⇪) - 21EA