There is no official way of doing this, but there is an unofficial way:
p { font-variant: prince-opentype(ccmp) }
Normally Prince will apply two OpenType features to Latin text, the "ccmp" feature for glyph composition and decomposition, and the "liga" feature for standard ligatures. Here we are overriding this and saying only apply the ccmp feature. You can also use this to apply discretionary ligatures, or other OpenType features if you like.