ActiveSync is the application used to shuttle files between the Windows operating system and the Pocket PC. It is used to install J on the Pocket PC.
It can be downloaded from Microsoft:
PocketPCs 2002-2003 use version 3.8
Windows Mobile 5.0 devices use version 4.1
Total Commander for Windows has a file system plugin for WinCE devices that allow all natural operations, such as viewing and editing text files, extracting arhives, etc. in addition to copying.
Total Commander for Pocket PC is a FREE but similarly powerful file manager that works on the device, and among other things, offers zip archive handling, text editor, FTP client, searching, and its own file system plugins, one of them -- to edit the registry as a file system.