To do this, you will need the Windows Script Host, which is installed on most versions of Windows. The latest version, Windows Script Host 5.6, is available by download from Microsoft's MSDN web site. The most recent version compatible with Windows 95 is Windows Script Host 5.5. You will also need the script launch_same_ie.js, available in the Downloads section.

Copylaunch_same_ie.js into your jEdit installation directory. Then go to Global Options>Plugin Options>InfoViewer, select "External Browser" and `type` the following in "External Browser Command":

wscript.exe "[full path]\launch_same_ie.js"

Once this is done, every time you invoke the InfoViewer, jEdit will run the script. It works by storing the window handle identifier for a particular instance of Internet Explorer in the Windows Registry (in the same location where jEditLauncher configuration data is stored). The script searches for the windows handle on the Windows desktop. If it finds the handle, it loads the requested file in that instance of Internet Explorer. If it cannot find the handle, it creates a new instance of Internet Explorer and stores the new windows handle.

Thanks to Dirk Moebius for the original version of this script.