I can't imagine it would do the grass seed, or the soil, much good, since its toxic. Just put down more seed so the birds have their share and there's enough left for grass.

yes but it wont grow. so no point at all.

I have previously heard of seed being treated with paraffin in just this way. I've never tried it myself though, and as Bamboo says, the idea of spreading something so toxic around the garden is not very appealing. Also I would doubt it could work on anything as fine or small as grass seed.....even if the seeds survived the process you wouldn't be able to sow it effectively since they would simply stick together in big lumps.