key_set (number, function);
Sets the given function to the key with the given scancode. This way keyboard remapping can be done very easily.
Parameters:
number scancode of key 
function pointer of function assigned to the key with given scancode  

Speed:
Fast 
Example:
Example for remapping a key: 
print("Please press key to assign function to");
while (key_any == 0) { wait(1); } // wait until a key is hit
str_cpy(my_str,"You have pressed ");
str_for_key(temp_str,key_lastpressed);
str_cat(my_str,temp_str);
print(my_str); // indicate which key
while (key_any == 1) { wait(1); } // wait until key is released
key_set(key_lastpressed,my_function); // assign function to key