This will require much more testing, but...
...I may have discovered a glitch that allows you to port World Tendency from a preexisting character slot. If you have the time and patience, please do the following to help confirm this glitch:
Have a full roster of characters in Demon's Souls.
Play as the first character on the list for a moment or two.
Create a new character in the bottom slot.
Play through the tutorial level.
After entering the Vanguard's boss room, manually quit using the XMB. This can be done at any time -- before or after killing the Vanguard.
Boot up Demon's Souls again, play the tutorial as before, and kill the Vanguard.
Upon reaching the Nexus, check your World Tendency. It should match the WT status of the first character on the list.
I don't know how many of these steps are necessary, but this is the process that has produced these results for me. I'm currently running through each world at Pure Black/White Tendency, without having died or slain any demons prior.
I also received a Guillotine Axe from a regular Boletarian soldier in Pure White Tendency, but I don't think that's related.