Not 100% sure but I assume that it would be the same as on my etrex 10.
Go into way point manager
select the way point you are after (in this case the cache)
A screen with the cache number, location, elevation, and map and OK buttons appear.
Press the button on the left hand side bottom (EDIT, just checked and it is called the menu button), this brings up a context menu.
Select Project Way point.
Enter bearing in degrees
Set projection distance units
Enter distance
It should then save
Select new way point under way point manager and navigate.