Here's some psuedo code...
code:
; Remote_Send.kix
; Resides on the remote PC. Is executed using WMI Remote Execute -OR-
; AT.exe -OR- JT.exe... $Requestor is piped in from the command line:
; KiX32.exe Remote_Send.kix $Requestor = "@WKSTA"
;
Break On
SetConsole("Hide")

$Answer=Inputbox("Hello")
$nul = SENDMESSAGE($REQUESTOR,$Answer)

Function Inputbox($Question)
; Your xls inputbox function here...
EndFunction