I found a work around for applications that need a drive letter.
Copy subst.exe from windows\system32 to your flash drive.
create a batch file with the following command.
subst.exe P: \
drive letter P: will be assigned to the flash drive you ran subst.exe from.
Now your flash drive will always have the same drive letter.
And yes this means it will actually have 2 drive letters, but P: will always be constant, it won't change.
when your done
run subst.exe /d P: to delete the drive letter, you can put this in a batch file as well.