Plotting power spectra of estimates on mne_analyze

Hi MNE users,

I want to plot on mne_analyze the power spectrum values of a set of
estimates obtained from a raw file. I got the estimates in matlab using
the forward matrix, the raw file and the noise covariance matrix but I
have not been able to create a file that mne_analyze can load and plot on
the cortex.

I understand mne_write_stc_file (although this one seems to be for time
domain files) or mne_write_w_file can help me but I am not sure how to use
them since I do not have a way to link channels and vertices.

Thank you very much for your help,