Code:
const int ClimbingFlag = 99;

global script Slot_2{
	void run(){
		while(true){
			//Other Global functions called before Waitdraw(); go here...
			
			
			Waitdraw();
			//Climbing script functions...
			if((Screen->ComboF[ComboAt(Link->X+8, Link->Y+9)] == ClimbingFlag || Screen->ComboI[ComboAt(Link->X+8, Link->Y+9)] == ClimbingFlag) && Link->Z == 0){
				Link->InputA = false;
				Link->InputB = false;
				Link->InputL = false;
 				Link->Dir = 0;
			}
			//Other Global Functions called after Waitdraw(); go here...
			
			
		Waitframe();
		}
	}
}
And now for Climbing number 3!

This time, it's a global script, as Waitdraw() doesn't work in FFC scripts.
It's by far more simple to use. All you have to do is add this in as your global script, and then all instances in the game of Flag 99 will become ladders.
Be wary that it'll only work with Diagonal Movement checked though.
If you want to change the flag it uses, just edit the integer at the top.

And if you want any help combining it with another global script (as we can only really have one), then I'll be happy to help =)