You didn't include a link to the plugin you were referring to (which would have made the question slightly easier to answer), but assuming I've found the one you had tried, it appears to have been untouched for the last 6 years. I assume it is compatible with Moodle 1.7, as Moodle 1.8 was not released until a couple of weeks after this plugin was last updated.
It is not possible to take a Moodle 1.x plugin and install it on a Moodle 2.x system, without at least some basic code changes (and in many cases, quite extensive code changes). If you don't have access to a developer to do this work for you (and assuming that the original developer has moved on a long time ago), you could always try looking for a local Moodle Partner ( http://www.moodle.com ) to employ to do the conversion (or to create a new plugin to your exact specification).