Puns are allowed. I would do it with puts. It's the same spread. By buying the July 5p and selling the June 5p, I have the position sometimes refered to as the Jelly Roll. I would be long synthetic stock with long call/short put with Junes and short synthetic stock with the short call/long put in the Julys. In such a position, the difference in price between the two different months synthetics is the cost of carry. Right now, the put time spread market is .25 bid at .55. If I could leg into the put spread for .30, I would essentially close down the position with a profit of .20.
In DNA, I did something different. I have a 1 by 2, buying 2 of the Jul 60c and selling 1 of the june 55c. It was done for a net debit of .05. Now when I say 1 by 2, I mean literally that was all I could get (delete pun) executed was 3 contracts at prices I liked. I think it was done for something like 13 points of vol edge.