I belive you would need a third party application or a full version of Autocad (not LT) in order to do any batch processing.
Full versions of Autocad 2004 contain this:
The Batch Plot utility builds a list of AutoCAD drawings to be plotted. You can use the list to plot immediately or save the list in a batch plot list (BP3) file. The Batch Plot utility (batchplt.exe) is located in the AutoCAD program folder. It is highly recommended that you use Design Publisher ( PUBLISH) to plot multiple drawings. You can use BP3 (batch plot list) files with Design Publisher.