latest version is 1.39, you will need to download it on another machine and then either burn it to disc, email it to yourself or put it on a usb pendrive to get it onto the infected machine.
once you have managed to get it on the machine, rename the file to anything other than the default mbam_setup.exe
yes this nasty can block programs from installing, run the newly named file and it should now run, id recommend changing the default install path ever so slightly (every little helps).
now that you have hopefully installed the program, make a copy of the mbam.exe file, rename it to anything else.
run your newly renamed file and it will load up, id recommend running a full scan.
once its finished scanning it will probably want you to restart your machine and its a good idea to do so.