Add Key Handler in VIMode Command set to $EditKey or Space by default to open commandline with console editor set in $EDITOR

Set-CommandLineEdit.ps1

Set-PSReadLineKeyHandler -VIMode Command -Key  $(@{$False="\";$True=$EditKey}[$(Test-Path Variable:EditKey)]) -ScriptBlock {
	if( Get-Command $EDITOR){ 
		# Grab BufferLine
		$Line = $Null
		$Cursor = $Null
		[Microsoft.PowerShell.PSConsoleReadLine]::GetBufferState([ref]$Line, [ref]$Cursor)
		# Launch Editor with temporary file
		$File = New-TemporaryFile
		Set-Content -Path $File -Value $Line
		if($EDITOR -match '[ng]?vim?'){
			Start-Process -wait $EDITOR -ArgumentList @($File, '-c ":set ft=ps1"', '-c ":set syntax=ps1"') -NoNewWindow
		}elseif($EDITOR -eq 'nano.exe'){
			Start-Process -wait $EDITOR -ArgumentList $File -NoNewWindow
		}else{
			Start-Process -wait $EDITOR -ArgumentList $File -NoNewWindow
		} 
		$Line = get-content $File
		# Write Command at prompt
		[Microsoft.PowerShell.PSConsoleReadLine]::RevertLine()
		$Line |% {
			[Microsoft.Powershell.PSConsoleReadLine]::Insert( $_.replace("`t",'  ') + "`n" ) 
		}
		Remove-Item $File
	}else {
		throw [System.IO.FileNotFoundException] "$Editor not found."
	}
}