|mc87: bump, just incase this has slipped into oblivion|
I'm not sure where you're pulling this Sleep() command from. As far as I know, it isn't in IE's DOM, nor is it a part of JScript. Are you sure Sleep(5) sleeps for 5 seconds, and not 5 milliseconds? Same thing with the logout command; it isn't in any POSIX compliant environment I use.
Without looking at the plink output, I'm probably not going to be much help.
All that said, if you do have the commands and waits correctly timed, you might get away with something like this:
Set oExec = objShell1.exec("C:\Program Files\Putty\plink.exe -ssh aserver -l auser -pw apassword")
oExec.StdIn.Writeline "su -"
'Assumed: supass is some password input DOM object thingy, and not a variable
oExec.StdIn.Writeline " ./blah/blah/blah start"
'Input sent; waiting for plink's exit
Do Until oExec.Status
oExec.StdIn.Write Chr(4) 'Ctrl-D
Textbox1.value = oExec.StdOut.ReadAll