Possum Help?

At the moment there is a baby possum clinging to our picket fence. Its quite young as it is about the size of a rat. Its mum is under our house (a queenslander on stilts) probably too scared to come out of its current hiding place. (In the bathroom wall.. which has a empty pipe leading out of it, which they use as a entrance/exit). I am a bit weary of going down and getting it because where I live, (Australia), possums have attacked humans and killed small dogs before. What do you think I should do?