Text insertion before a number on 10,000 text lines possible?

I figure it could be possible to do it with a macro or action script of sorts however one would need to start from the last line forward as the text inserted will need to be 3 lines or more itself and that would make the line seeking not work properly if started from the beginning.. Below is example of what I am trying to achieve..

111111
222222
333333
444444
555555

turned into this 10,000 times automated in a batch file?

Please post a reply as what application I should be using if any you know of out there?

below is what the end 10,000 lines turned into 40,000 should look like...

SAME TEXT SAME TEXT 111111
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT 222222
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT 333333
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT 444444
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT
SAME TEXT SAME TEXT 555555

If you think I will have do this by hand please also post a reply.. Thanks for reading this.. 2 word comments are fine.. Cheers