TableTools - Define export columns programmatically

Gnorro1976

Hi

I know I can define columns to export with:
"mColumns": [0,1,3,4,5,6,11,12] inside "aButtons".

But I need to define colums to export programmatically depending on user profile.

I know I can use:
"fnClick": function( nButton, oConfig, flash ) {
...
this.fnGetTableData(oConfig);
}

to catch event ad do something. But how can I "modify" the oConfig object to define that?

thanks