Plugin by diddy
Download Plugin (.zip)
Download Plugin (.7z)
Download latest 7-zip from here
7-zip is a freeware file archiver with support for packing and unpacking 7z, ZIP, GZIP, BZIP2, and TAR archives. It also supports unpacking RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB and NSIS archives.
Download the latest version of 7-zip and install it (using default locations). Copy the contents from C:\Program Files/7-zip (including sub folders) to the plugin/7-zip/files directory. Edit plugin/7-zip/7-zip.inf to change language settings (default is English) and to add file associations (only .7z is enabled as default).
*NOTE* - This plugin is based on 7-zip version 4.42, but should work with newer versions. If any additional archive formats (or languages) are supported in newer versions you will have to manually add entries for them in plugin/7-zip/7-zip.inf