Well, I haven't used 98 in ages, but I do know of a tool that lets you kill processes via command line.
For taskkill, you could try and save the taskkill program to a disc or something and copy it over to the win98 machine.
For the other app, pv.exe, you can download PrcView, which comes with the command line program "pv.exe"
http://www.faratasystems.com/pview/prcview.htm (download)
http://makemsi-manual.dennisbareis.com/pv_exe.htm (info)