Hi,
You can select the whole dataset and then go trough all pushpins and change the symbol. I dont know how fast it will be, but I think it also take a few seconds.
You can also use AddPushPin and set eacht symbol, but it will be slower for such amount I think. Note that the speed is depending, if you use same name or empty name then it is slower, with exclusive name for each pushpin it is faster.