Add nuisance regressors in 3dNLfim

Hello,

We are using 3dNLfim to estimate the shape of the HRF for a breath-hold response. Since the estimate is a bit noisy, we would like to add a set of nuisance regressors in the model (e.g. drifts, motion parameters).
Is it possible to add a set of nuisance regressors in the noise part of the model in 3dNLfim?
Could this be actually implemented in Linear+Ort noise model available in the program?

Thanks in advance for any suggestions,
Cesar