Has anybody got any idea how to tune this patch I whipped up earlier? The problem is that the centre frequency values for the phaser don't correspondto any notes. I couldn't think of any way around it.

In typical applications of multipole phasers the relation between the centerfrequency and the distance of the peaks and valleys is deliberately non-linear over the frequency range. You might want to use bandpassfilters instead. Here is an example of an aetherical noisy organ where three uncorrelated noise sources, bandpassfilters and ringmodulators (AM input in the sine slaves) are used. With the partial module you can set the harmonic for a bandpassfilter, but watch out: the reading on the module does not reflect the actual setting (little bug in the editor, I suppose), set them by ear.