Here you can find list of different color schemes for syntax highlighting which can be used in HippoEDIT.
How to install extension with 1.50 and higher:
download bundle file (*.hebundle) and open it with HippoEDIT. Or use editor built-in on-line repository functionality.
How to install extension with 1.4x and below:
get extension using download link from the list, rename *.hebundle file to *.zip and unpack the archive into user data folder (current path can be found in About Box).