From Eggdrop Wiki
This will enable your Eggdrop with UTF-8 support.
Notice: Use at your own risk, as this may not solve all your encoding problems.
Open the eggdrop1.6.21/src/main.h file in your editor.
Search for (around line 46)
and replace it with
Open the eggdrop1.6.21/src/tcl.c file in your editor.
Search for (around line 650)
and insert the following right after it
As an alternative to patching your bot with the patch above, you can also use this script.