As you easily note, I am new here and english is not my first language: so, be gentle please.
I am using a windows 7 machine with MiKTeX installed (just in case).
I have the following directory structure (in a pendrive, named D in my system):
I have created the file finger.sty in the fourth folder and I have tex files in the first three folders: I want to use finger.sty file (via \usepackage) in those tex files.
For portability reasons, I want to use the folder \step in different machines with different TeX directories structures (I don't want to touch them) and, possibly, naming my pendrive with different letters.
For maintenance reasons, I don't want to have a copy of finger.sty file anywhere but the fourth folder.
How could it be possible to satisfy all my requirements (wishes)?