Apple - Can I select only a few specific folders to back up with Time Machine?

You may exclude items from a Time Machine backup as follows:

1. Open System Preferences.
2. Click Time Machine.
3. After having enabled Time Machine and chosen a backup disk, click Options.
4. Click + to specify an item that is not to be backed up. The backup disk is included on this list automatically so that it does not back up itself.

Easily - no. Time Machine's selection only uses exclusion so you'd have to exclude everything but the folders you want. I'd recommend looking at a different solution instead (eg. rsync, Retrospect, or other backup software)

Select All the files and folders in the disc that contains the folder you want to back up.

Drop them all on the Exclusions window

Remove the folder you want backed up from the exclusions