Iceweasel 26, no root privileges and ad blocking

In our workstations we don't have root privileges. Our home directories are synced (they don't depend on the physical computer). We have an old Iceweasel 26 installed. I'd like to block the ads. Unfortunately, Adblock Plus is not compatible with Iceweasel 26. I'd use /etc/hosts, but, as far as I know, I can't set up user-specific /etc/hosts. I considered setting up my own local Firefox, but our home directory is limited to 768MB, so I don't think it's a good idea. What would be an optimal solution in my case? Is taking an old version of ABP the only way out?