Adding a column in a tab delimited txt file

[Garry]

Hi, I am new to python, hope someone can help me here:
I have a MS Access exported .txt file which is tab delimited in total
20 columns, now I need to add another column of zero at the 4th column
position and a column of zero at the 9th column position. What is the
best way to do this? Can I write a while loop to count the number of
tab I hit until the counter is 4 and then add a zero in between and
thru the whole file?

Thanks,
Garry