Printing chord names between the staves of a PianoStaff

[Onni Koskinen]

I'm new to LilyPond but I already feel impressed. Anyway, I have one 
problem: I'd like chord names to be printed between the two staves of a 
PianoStaff. I did a quick search of the archives but couldn't find help 
there.

I know it's possible with normal staves, like this:

score = \new Score <<
 \new Staff \righthand
 \new ChordNames \chordlist
 \new Staff \lefthand
>>

I tried the following, but the chord names got printed beneath the two 
staves.

score = \new Score {
 \new PianoStaff <<
  \new Staff \righthand
  \new ChordNames \chordlist
  \new Staff \lefthand
 >>
}

I'm using LilyPond 2.4.2. Any help would be appreciated.