||Take at look at the VB help topic and example for the "Command" function. In the Sub Main where your app starts, use this function to get arguments fed to the app on the command line. In the case of your app, your command line might look something like this:
txt2shape.exe txtfile.txt output.shp
...so your batch file will simply be a list of these "txt2shape.exe" calls. If you don't have the batch file made already, and you only have a list of text files, or a folder full of text files you want converted into shapefiles, then perhaps only have the command line argument give the path of the folder. Then in Sub Main, cycle through that folder, and for each *.txt file, convert it into a shapefile.