Using Maverick's tags on Mountain Lion I have multiple macs accessing same data on a common disk (a time-capsule shared disk). The problem is that one of those macs couldn't be upgraded do Mavericks (it's running Lion).

Is there any app that I could install on a non-Mavericks mac to use it's tag system?
In another way: Is it possible to "read" Mavericks tags from a lion mac using any kind of software?

UPDATE: Originally I mentioned Mountain Lion, but in fact, my older Mac is running 10.7.5 (Lion).

UPDATE(2): Support at Iconic software did mentioned that their tagging software (Leap - the paid version - not Taggit, the free one) is now compatible with Mavericks and that it will try to convert native tags to their format of tagging. Since this software (Iconic Leap) is compatible with OS 10.7+ and above, it would be a tool for sharing tags between OSes versions. Will try this out and post back the result for future reference.
Tags in Mavericks are actually partially backward compatible with labels in Mountain Lion, because they're implemented as sort of an extension (and renaming) of labels. The main issues are:


If you assign multiple tags to a file in Mavericks, Mountain Lion will only see the most recent tag (label)
Tag colors aren't preserved; e.g., if a red tag in Mavericks shares the same name as a blue label in Mountain Lion (say "Important"), it'll appear in blue on Mountain Lion


All that said, why can't you upgrade your Mountain Lion system to Mavericks? The system requirements didn't change, so any machine that can run Mountain Lion can be upgraded to Mavericks.