If you want, you could create new putserv, putquick, and puthelp commands. Then check the message to see if it's a privmsg to a channel, log it if it is, and pass it on to the real putserv/putquick/puthelp.
Use the tcl "rename" command to rename the old commands, then create new ones in their place.
but i was wondering if eggdrop has the builtin functionality to make itself log its own msgs like other users without me having to go to all this trouble...
I do not know if this is going to be a direct feature, but work that is being done on the complete rewrite will allow this.
Both the input and output queues are being changes so they can be edited before they reach the main processing points.
This will allow third-party addons (at least) to create outbound traffic logging, including customised statistics, and internal based traffic debugging.