You should try the FAQ on the FIC web site (Taîwan english version)
http://www.fic.com.tw
You will see jumper settings for all K6-x CPU's. If you want to overclock, you can use up to 5.5 clock multiplier and if needed, the 2x=6x remapping allowed by the CPU.
For K6-x+ CPU's, read carefully the FAQ. They speak about a new BIOS release but mobile versions of the K6-x (the +) are not officially supported. Try it at your own risk.