Is there a non-Java implementation of the M5P regression model of the RWeka library?

Question

I am looking for a function which creates the M5P regression model like the M5P function of the RWeka library (as the M5P function is based on Java code which has some drawbacks for me). I tried the cubist function of the cubist library and the rpart function of the rpart library. These two models did not perform as good as the model from RWeka and also their out-of-sample predictions seem to be capped (increasing the input parameters of the model after a certain point does not increase the prediction value), whereas the model from RWeka can predict higher values with high input parameters (which I would like to be able to do).Thanks!