I believe this feature is already present
Right click on the channel tab in the switchbar and go to 'Logging' and then check the 'On' option so there's a tick next to it. This will enable logging just for that channel.
Also sort out your current Logging settings in ALT+O > IRC > Logging and make sure the drop down list either says 'Queries' or 'None' otherwise it will keep logging all channels.
Hope this helps
Regards,
