Most third-party plug-ins designed for Mozilla/Netscape will also work with K-Meleon. These include:
Most of the time you can follow the Mozilla instructions in Mozilla & Netscape 7.1 Plugin support on Microsoft Windows, but some plug-ins try to detect what browser they are really used by. This causes problems since K-Meleon is neither Netscape nor Mozilla. The Mozilla Firebird Browser has the same problem which has been carefully documented. Use those instructions when needed.
See also the page "Third-party plugins in K-Meleon", by Andres Aule. (dead link)