>>You don't need a Factory (at least for this bit):

public class SomeClass
>> {
>>     private SomeClass()
>>      {
>>      }
>>      public static SomeClass GetInstance()
>>      {
>>        return new SomeClass();
>>      }
>> }
>>
>>//To instantiate:
>>SomeClass sc = SomeClass.GetInstance();
>>// This won't compile:
>>SomeClass sc2 = new SomeClass();

>
>Then this defeats the whole purpose. I don't want the class to be created from outside my factory. I want to be able to set things
>on the instance before returning it to the caller.

Then I think your options are limited. Either
(a) Create a CTOR for the class with parameters that accept the values you want to set
or
(b) Make the class private and hide it behind an interface.