alt+codes+for+special+symbols

make sure the num lock key is on, hold down the alt key to the left of the space bar, then use the number pad to type the number for your special symbol.

webpage with instructions http://usefulshortcuts.com/alt-codes/instructions-for-using-alt-Codes.php list of alt codes for a few greek letters http://usefulshortcuts.com/alt-codes/greek-alt-codes.php

lambda -> 955 mu-> 230