Unfortunately, you can only turn on all invisible (whitespace) characters at the same time. I suggest you file an enhancement request but I doubt they will pick it up.
The text component in Eclipse is very complicated as it is and they are not keen on making them even worse.
[UPDATE] This has been fixed in Eclipse 3.7: Go to Window > Preferences > General > Editors > Text Editors
Click on the link “whitespace characters” to fine tune what should be shown.
Kudos go to John Isaacks