What you describe is possible in the GUI. If you already EEG signals imported in 100ms blocks, and have their sources with them, just place those source files (
or 
) in the Process1 tab, click on [Run] and select the process Extract > Scout time series.
When data is imported as blocks, they have the original time definition, so you need to either:
-
Check the option All file in the process Extract > Scout time series, or
-
Make uniform their time axis as shown in here:
https://neuroimage.usc.edu/brainstorm/Tutorials/CorticomuscularCoherence#Epoching
If you want to write scripts to automate some task in Brainstorm, all the information you need is in this tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/Scripting