As long as you did not delete the old version of TinyMCE from under /ClientScript/tiny_mce358
then you can change back to that version of TinyMCE by adding this in user.config:
<add key="TinyMCE:UseV4" value="false" />
<add key="TinyMCE:ConfigFile" value="mojoTinyMCE.config" />
<add key="TinyMCE:BasePath" value="~/ClientScript/tiny_mce358/" />
Then touch Web.config or recycle the app pool to make it reload settings.
Hope that helps,