as an replacement for ksh under cygwin, pdksh might be the only choice. but look like there have a bug for cygwin : pdksh(5.2.14-3) to support backslash path (\).
it will swallow the \ :
$ cd .\access
pdksh: cd: /cygdrive/e/.access - No such file or directory
After search on the internet, the same problem solved for other platform. but no idea how to solve it for cygwin.
You have to use forward slashes, or double all the backslashes, or single-quote every string that might be a pathname. Sorry, there's no way around this. This is a general problem with trying to use Unix shells, for which \ is an escape character, on Windows.