Writing Plugins for Numbers / Exporting into a non-standard format

Hello all together,

maybe it's already somewhere on the net, but I didn't find it..

Is there any possibility to write sort of a "plugin" for Numbers? What I would like to do is export data to a specific format thats not already covered by Numbers' export function, let's say to use it with Grapher or the open source Software "Plot".

At the moment I export the data into a CSV-File, replace all quotes and change the numbering format from the German to the English one (using a dot as the decimal separator, whereas in Germany it's a comma) - this, however, takes some time...

So, if there is a possibility to write an addition to the traditional Export-Dialog, it would be great if you could give me a hint where to start.

Thanks in advance,
Alexander Hofmann.