This sounds like something more suited to a view scheme or smartlist than a search.
Just create a view scheme in JRMC with the appropriate rule and view the list in the library via NR.
Also - I assume you are using KingSparta's plug in to create these comments. If so you can set it to put the chart position in a custom field of your choice. Just set up a custom field called Chart Pos making it an Integer field rather than string. Then change the settings in Sparta's plugin. Then you can create a rule of 'Chart Pos <4'.
You may need to go back over your existing tracks and back fill the new chart pos field but that's not that big a job if you think it through properly!
OpusNR & JLee CCF/GML available in the downloads section.