I don't think that strike exists as ascii code, and I don't think it could be supported by IRC servers.
AFAIK, you can only use:
\003 => colors
\002 => bold
\037 => underline
\026 => italic / inverted (not supported by all ircds)
Strikethrough letters for ASSCI are supported. I've already tested on the Dalnet network, and I've also tested on the ChatZona network and it supports it.
If there is a crossed-out ASCII code for IRC and I have tested it on the dalnet and chatzona networks to see if they support it.