Is there a way to put on a vertical spread where both legs of the trade are executed at once for a single credit or debit?
Yes, but it’s a broker-specific thing (that is, how easy they make it to order spreads: vertical, diagonal, whatever). My most recent option spread trading was at TradeKing, and spreads were very easy to put on… choose Trading->Options->Spread, enter an underlying, choose the strikes for each leg and the net credit/debit you’re willing to take as a limit order and say Go. No need to specify the precise prices, just the debit or credit between them. Everything is displayed on one easy form, you can see at the same time both legs, and a little refreshable panel to show the realtime bid and ask prices so you know just what you’re ordering wrt current bid-ask when it goes in. I imagine some spread ordering interfaces are not so intuitive or easy as theirs.
If instead you’re asking about using the C2 interface for entering vertical spread orders… I have no idea, it may not be so intuitive. 
C2 does recognize margin requirements for options spreads , but you cant enter legs as a single trade , you have to manually leg-in at C2 .
Ok, thank you for your responses.
