Why do you try something complicate? The .ipk extension is just a .tgz (tar gunzip) file, change the extension to .tgz and you can open it up with any decompressor on PC or use:
tar -xvzf myipk.tgz
Pr2
No. It's an ar archive.
To unpack it just execute this on the box:
ar x file.ipk
Then a control.tar.gz, a data.tar.gz and a debian-binary is generated.