You should probably ask yourself whether this is really the way you want to go. First of all, you don't feel like defining one hundred methods for one hundred hash keys. But say you find a way, you still have at least one hundred different calls, so are you ok with that? It will be very difficult to let your program grow.
Why don't you try to understand 'objects' (that is, blessed references) first, define a getter, a setter and making the key as one of the arguments. The getter and setter methods can validate the input for you.
If you really insist and if you are prepared to follow the narrow, steep, winding path you could use a method called AUTOLOAD; this method will be called in case the requested method can not be found. It allows you to examine the method that was called, so you can extract the desired key from the method. In fact, the O'Reilly book "Perl Objects, References and Modules", chapter 11 (or its successor "Intermediate Perl") describes how to do just what you want.