I need help writing a position independent CMD script

I need help writing a position independent CMD script.

I'm helping a friend write a CMD script that is called by
another script in windows 7.

It does a lot of stuff, but the issue is encapsulated by the following...

Directory structure is
D:\
program root directory
dir1
somefiles
dir2
copyscript.bat

The copyscript.bat is one line

xcopy dir1\*.* dir2


The script works fine when executed from program root directory.
But it's called from a script on another partition.
Xcopy can't find dir1 or dir2. It's looking in system32.

The current workaround is to add the following

D:
cd pathto program root directory

That fixes the problem, but it's position dependent.

How do we modify the script so that it runs no matter
where program root directory is? How can the script
determine it's location?

In the current context, it's executed from task scheduler.
Task scheduler allows inputting the working directory.
That's not the question.
Ditto for calling the script thru a shortcut.

I want to learn the path syntax for writing a self-contained
position-independent
CMD script that uses relative addressing in the version of CMD interpreter
that's in win7.
Explanations and links are fine, but the ideal answer would also edit
the above one-line script to make it position independent. The devil is
in the details.

I've already googled my ass off. I'm lost in escape sequences
and parentheses and pre-defined system variables and
the fact that CMD lines may parse differently if they're in a script.
Using a different scripting language won't help. I'd have to learn it
and teach it and become "customer support" forever. That's way beyond
what I'm willing to do.