Pen + Paper and a matchbook.
You still gotta magically import that data from your paper onto your computer without a keylogger fucking you which is impossible if you are infected with one. No matter what you do if you have a keylogger installed and you are not aware of it then you can't find a special way of inputing something....especially these devices which claim to be keylogger proof because you type through a external piece of kit...thats bullshit and acts the same as a keyboard.
You can only take precautions;
1. Anti Virus installed
2. Know what processors are supposed to be running. (clean install & note trusted programs which you install)
3. Install/download anything not from a legit source on a virtual machine through VMware or something similar.
4. Know your filesystem inside out.
5. Use a password manager such as lastpass...good for not forgetting passwords too and is very beneficial....everything is encrypted on sever side.
6. Download Noscript & httpeverywhere extensions & disable javascript on your browser.
7. Don't be a arsehole.