What do you mean with "model the dipoles of a pre-selected set of scouts"?
If you are using simulations to generate MEG or EEG recordings, you already know your dipole activity, and you simply want to multiply it with the forward model to obtain the corresponding explained recordings.
in simulate recordings in the scout tab, is it advisable to feed the script with a noise profile
Using this menu, there is no noise added to the simulated EEG/MEG data. You already start from an existing source file.
In the process "Simulate > Simulate recordings from scouts", you can attach a signal to a scout, generate a source file and compute the corresponding modelled MEG or EEG recordings. Only in this process you can add noise to the sources, and then noise to the recordings (which is generated using the the noise covariance matrix)
See for instance this thread: Simulate scalp recording - #3 by Wisal_Siyam