How to create a bootstrap.dat file?
Since van der Woerdt's answer in first question you link to indicates you can simply concatenate the blk files, you can open a DOS window (if your using windows), then type

CD C:\Users\&lt;my_user&gt;\AppData\Roaming\DogeCoin


(if you're on Win7+)

And then

COPY /b blk0001.dat+blk0002.dat bootstrap.dat


And that would be it!