There is a recently developed plugin for Pidgin that works quite well. Basic things such as chatting, buddyicons and sending files are all supported. You can use it by adding ppa:lainme/pidgin-lwqq to your repositories and then install pidgin-lwqq. After that WebQQ shows up in the list of protocols to choose from when adding a new account in Pidgin.

sudo apt-add-repository ppa:lainme/pidgin-lwqq

sudo apt-get update

sudo apt-get install pidgin-lwqq