This can be done using the ztree.inf install utility

Below is the explanation in the beginning of ztree.inf
;==============================================================================
;
; This will install ZTree into the Drive and Folder context menus of Explorer.
;
; Once installed, you can right-click on any Drive or Folder, then click
; ZTree on the menu to start it at that location.
;
;------------------------------------------------------------------------------
;
; To install in Windows 95 or 98:
;
; Using Explorer, create a shortcut to the installed ZTWIN.BAT file
; in the installed ZTree folder. Name the shortcut "Ztwin",
; (not "Ztwin.bat").
;
; Modify the ZTWIN shortcut properties, Program tab, as follows:
;
; - Clear the Working entry
; - Check Close on exit
;
; Modify this ZTREE.INF file's ZTRun line under [Strings] to the
; installed ZTree path.
;
; Run Explorer, right-click on this INF file, click Install.
;
; Note: Due to a bug in the Windows 95 setupx.dll program,
; if you've installed ZTree in a folder which results
; in a long file name path, such as C:\Program Files\ZTree,
; the install program will be unable to find this ZTree.inf
; file automatically, and you will get an "Insert Disk"
; message. Simply Browse to the folder which contains
; this file and click OK.
;
; To uninstall, use Add/Remove Programs in the Control Panel.
;
;------------------------------------------------------------------------------
;
; To install in Windows NT:
;
; Modify this ZTREE.INF file's ZTRunNT line under [Strings] to the
; installed ZTree path.
;
; Run Explorer, right-click on this INF file, click Install.
;
; To uninstall, use Add/Remove Programs in the Control Panel.
;
;==============================================================================