If you just want to select a specified column or columns, you can do it either by column number or name as shown in the first few lines below. If you want to do it interactively, use the Column Dialog command: I've included below an example of how you could use it to select a third column in addition to the first two:
style="font-size: 9pt; font-family: "Courier New"; color: green;">/* If the final item in the list is the 'OK' button then assign the 3rd column */ style="font-size: 9pt; font-family: "Courier New"; color: black;">
I don't know of any direct way to open only selected columns via scripting (though it may be possible) but it may be of interest to note that if your file is stored as an Excel file or an Access database or any other kind of file that has an ODBC driver installed, then you could use the Open Database command with SQL to select and load only the desired columns.
I feel completely sure that there's no way to get a column listing without first opening the data table.
And David: I think you've got the best way of detecting the OK button. There's no specific routine to do this. It all comes down to the fact that the dialog returns a list, aht you've got to use generic list processing thingees to examine it.