I don’t think there’s a really easy solution for that (in case there is, I’m curious as well).
Based on some previous work, I’ve come up a workaround which involves converting your image to an SVG, adding the text layer and then (if necessary) convert it back into a pixel image. The core solution is in the Java Snippet node:
You can find the workflow on my NodePit Space:
Feedback welcome!
– Philipp