The DCO generates a wave running from 0 to -10V. To center this, I tried using two resistors and a 1uF capacitor, followed by a buffer. This works fine for higher frequencies, but at the bottom of the frequency range we get severe distortion, turning the straight lined saw wave into a slope.
Also, this arrangement won't work for Pulse signals as the pulse width has more energy at either top or bottom.
The square and pulse waves are a bit interesting as the amplitude CV does not have to run through a VCA. Instead, the amplitude is equal to the CV. This means that subtracting half the CV from the output wave will center it.
I've come up with the following, untested (and incomplete) circuit that shows my idea: