Try the following formations...

Nickel - Monster Green or a spy formation. Monster Green provides one linebacker on a blitz up the middle and a CB on a blitz from the side. Make sure your blitzing CB is coming from the opposite side of his two WR's.

If you go with a spy play in the nickel formation it gives you 5 DB's to protect against the pass in zone coverage and one LB for pass protection (most likely to cover the zone of the WR on the crossing route). The other LB stays in his spot anticipating the run.

You could also go with a Nickel formation Cover 2 scheme. The cover two only gives you two DB's for deep threats but it blankets the 1st down marker with CB's and LB's on pass protection. You could take on of your LB's and fake the zone protection. When you friend snaps the ball bring the LB up to stop the run or shift to the the player closest to the ball.

Despite what you've said about Dime coverage. I would also look at Monster Green in a Dime formation. That way you've got man coverage on both of the WRs. You will have the CB and LB blitzing to keep his QB from having much time to throw. I would also select one of your middle two D-linemen before the snap. As soon as he snaps the ball go into a rip/swim motion to break down the protection. If he runs the ball that D-lineman will likely make the stop. If you don't see run immediately switch to your nearest DB.

I would also recommend that you practice this. Go into practice mode and pick the two teams you guys play with. Select his offensive formations and try the above D formations. If they are from the same offensive set than select random play from this formation and it will keep you on your toes.