Actually you can do it without B-sticking, by holding down A (or I set my attack to Z to make DAC's easier, helps for this as well) before you draw the bomb / as you are drawing it. Then you can run around or whatver, and hit the C-stick for the side smashes.
From my experience, Up-smash does nothing, D-smash just makes you crouch for a tiny bit then stand again, even if you hold it down. Letting go of the C-stick after you start will not cancel it early, and it will only attack after the charge is finished, as well as only doing the first hit. In order to cancel the full charge / do the second hit, you'll need to let-go / press the attack button twice. However, the good news is you can hold it down after the second hit of the smash, and you'll be set up to do it all over again.
If you act quickly, you can get off 3 pairs of F-smashes and still have time to throw the bomb about 1/3 of FD before it explodes. I can upload something in a bit if that didn't make any sense, I only woke up about 20 minutes ago and my brain hasn't turned on yet.
EDIT: It works with held-items off the ground too, just hold down the button you use to pick them up before you start the smashes.
EDIT EDIT lol: If you're holding an item and you let go of your attack button for whatever reason, just throw GB, fire an arrow, roll, or whatever. Hold your attack button down while he's doing that, then when you come out you'll be good to go.