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It might be possible to tie into the horn circuit or the illumination circuit of any lights on the wheel, but the airbag circuit should be left alone. Also don't physically block the airbag.
Use clear silicone sealant (most economically had in cartridges for caulking guns) and yes, they will probably be dishwasher proof. I'd still test them though because the candlestick glass might not withstand the treatment.