My educated guess tells me that it's caped on the 2nd fret, playing the A minor chord, making it in the key of B minor and Jorma fingerpicks the intro on the recording while Paul uses a flat pick in concert.
On the recording you can hear Jorma "pull off" the 2nd and 3rd strings of the A minor first position chord. Paul plays it like he's done on countless other songs (intro to Have You Seen The Saucers for one) as demonstrated here:
e|---------------------------------------------------------------------------------------------------------|
B|----------------------------------------------------------------------------------------------------------|
G|-------------------5------------------------4-----------------------0-----------------------------------|
D|-------------------7------------------------5-----------------------2----------------------4------------|
A|--------0----------------------0------------------------0----------------------0-----------5------------|
E|----------------------------------------------------------------------------------------------------------|
It's a magical 12 string moment on Takes Off. Perhaps my favorite JA album, for now anyway.

