I've just pm'd you a link to the exact installer I used.
Basically, the instructions for installing that are as follows:
1: extract the rar file to a folder in the root of your C: drive (c:\inpainstall)
2: run the "instprog.exe" file in the "INSTALL" folder (c:\inpainstall\install\instprog.exe)
3: Click ok to the german message box that appears (starts with "Haben Sie Probleme bei der Installation?")
4: Select "English" in the language selection, then click "Continue"
5: when the "Viewing the reference lists" page is shown, click "Continue" again.
6: Ensure "C:" is selected on the "destination drive" page, then click "Continue".
7: Select "BMW Group Rectification Programs UK" from the "configuration" page, then click "Continue".
8: Select "Complete" next to "INPA", then click "Continue".
9: Select "OBD (on board diagnostic plug)" from the "Interface" page, then click "Continue".
10: Click "Continue" on the "starting the installation" page.
11: Click "End" when the installation has completed.
(It's likely that the installer will hang after you click End.. don't worry

)
That should give you a full working version of INPA.
It will be configured to use COM1 for your interface cable.
If your cable isn't configured to COM1, you can either change that in Windows Device Manager, or go into the OBD.ini file in C:\EDIABAS\BIN and change it from COM1 to the com port your cable is on.
Then you really should be golden!
