How do i get my ps3 online with a usb modem

Ok dunno if this has been covered at all before but just thought i'd ask. I have a current plan on the internet with a USB modem which i just chuck in my laptop, now i've heard all diffferent ways of going online with the ps3 but have never heard of people using a usb modem, can i just run an ethernet cable from my laptop the PS3 with the USB modem running? I dont have a house line and dont intend to get one just for online gaming and i don't wanna change my current internet plan coz its just fine the way it is.
Any help would be appreciated cheers.