Start by getting the Flick upload action and install it according to the instruction on that page.
This action uploads any image file that you feed into it. Don’t bother to set the title, description and tags, because it extracts them from the metadata in Lightroom (do set them there ofcourse)
If you start Automator.app you should see ‘Flickr’ under ‘Applications’, and in Flickr an ‘Upload to flickr’ action that takes images files.
I created a workflow that consists of the following steps:
- Get folder contents
- Filter Finder items (whose file type is JPEG image)
- Upload to Flickr
- Move to Trash (because I export them from RAW, and don’t need to keep the jpegs around after uploading)
Save this workflow as a plug-in (Command,Shift,S) and select Folder Action.
Select and/or create a folder where you will export your jpegs.
Then in Lightroom go to File - Export.
Select the destination folder your you selected for the Folder Action.
I changed my file naming template to ‘custom settings’, and used (Title)-(Orginal File Name), but you can choose anything.
Set the other settings to what you like, and then select ‘Preset -> Save as new preset’ at the top of this dialog. I named mine ‘Upload to Flickr’
I clicked ‘Export’ and then there was a problem; the folder action came up after the first image was put up, instead of waiting until all where exported. To solve this I added a ‘wait for user input’ step in front of the first step in automator. Suggestions for a more elegant solution welcome 
