Need details about 3 debranding Sweden K850

Been googling around all kinds of forums and still not totally sure about the process.

I want to get rid of everything that has with 3network to do in my K850.
I understand that A2uploader is the right thing for me.
And I need to have 2 files, as Generic and Main.
Then I also need a custom file?

I´ve done this before with an W890i, but it didn´t work that well. Still got some 3 stuff into the phone.

Could you help me to describe exactly which files I need for an K850 and my network is 3,Sweden. Do I need an nordic version or the Hutchison?
Any differences between the numbers of the files in the download section?

Another question, what´s the deal with the custom file? If I download something with Sweden.3 into the filename, doesn´t it install 3´s stuff back into the phone?

Perhaps everything are already described in the forums, but I´d checked and I am just so confused right now. :eek:

Edit: Details about the phone:
R1CA029 Hutchison, feels like an very old version?
More info needed

Never mind about the above question.
I did it in another way.

I used the A2 CDA file Generator application instead.
I just simply uploaded an customize_upgrade.xml-file into the phone by A2uploader.
And then with SEUS, the magic happened. It took away the awful menus, upgraded and
made my phone as good as new. Now I got nothing to do with 3 anymore!
Gotta love it!