My DS4 is also battling a cough, and since we leave for WDW in two weeks I am attacking it with fervor!

I regretfully don't have any "home remedies," but I can tell you some things that have been helping us:
1.) I give him Airborne every morning. Not sure if it helps or not, but if there is even a small chance that it will cut off even a few days of this cold, I'm willing to try.
2.) Mucinex. This helps us because my DS's cough is a "mucus" kind of cough.
3.) Vicks vapo rub. I slather it on his chest in the morning and at night.
4.) Vapor-Plug-ins. We use the Sudacare brand. It's basically a menthol-type plug in that you use during the night. I have found it to be one of the most helpful items I have found since the "cold medicine recall" came into effect.
I was just at my pediatrician's office this morning, and he actually told me that as a VERY LAST RESORT I could give my DS some cough suppresent (and cough suppresent only, not a cold remedy mix) at the minimal dosage. Obviously this is only the recommendation of one pediatrician, and I know all parents are struggling with the cold medicine recall in their own ways. I just thought you might be interested to know that not all peds think all meds need to be out of limits at all times. (And just for the record, our pediatrician's office is a large practice, with a high percentage of highly respected doctors who were Chief Pediatric Residents.) Regardless, I do not condone or suggest you should follow this advice - just know that it was given.
Good luck - I can totally empathize with you right now. Do try those Vapor plug ins - their wonderful.