Well, Im not going to do it for you, ubut i can tell you how to do it.
With the standard .dll injector, the code pretty much says:
If you click inject, it will find a certain file and inject it.
The code of simple .dll injectors looks for the name of the .dll injector.
EX) If you name your .dll inejctor SimpleInj.exe, it will inject a file called SimpleInj.dll.
What you need to do is find in the code where it states it will inject the name of the injector.. and change it to something like
....Then (insert inject code here) "MsgBox1.text".
This way it will inject whatever is typed into Message Box 1.
If you have any questions, PM me.
(In order to edit the code this way, you must read the code carefully.. for in some cases if you change the path of the .dll to "MsgBox1.text" you will have to change it in another spot of the code, as well.)
Please Click thanks If I helped.
EDIT: Wasn't paying attention to question.... sorry