It won't do MapInfo tab files but it will do MapInfo mif/mid files. If you have MapInfo Pro you can export them to mif/mid easily or you can use a free tool like -- FWTools: Open Source GIS/RS Binary Kit There is supposed to be a command-line tool ogr2ogr that will do conversions. Or -- MITAB - MapInfo .TAB and .MIF/.MID Read/Write Library see tab2tab.

I know that at one time Mapping Solutions extended the Spatial Data Importer to support importing tab files directly but I don't see it in their product list, you might contact them.

I have done a lot of customizations of the Spatial Data Importer myself, mainly just to perform thematics or coloring based on some variable or variables and also doing automatic labeling.

Eric