Help for SET PREFIX:

PREFIX allows you to customize the channel fantasy trigger
for your channel. This is particularly useful if you have
channel bots that conflict with ChanServ's default fantasy
prefix. Providing no prefix argument (or DEFAULT) resets
the channel fantasy prefix to the network default prefix.

Syntax: SET <#channel> PREFIX [prefix]

Examples:
    /msg &nick& SET #foo PREFIX
    /msg &nick& SET #foo PREFIX '
    /msg &nick& SET #c PREFIX %
    /msg &nick& SET #c PREFIX default
