PowerShellでクリップボードを使う。: Windows Script Programming

http://scripting.cocolog-nifty.com/blog/2007/08/powershell_1b86.html

[Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
$textbox = new-object System.Windows.Forms.TextBox
$textbox.Multiline = $true
$textbox.Text = "あいうえお"
$textbox.SelectAll()
$textbox.Copy()
$textbox.Paste()
write-output $textbox.Text