It depends how your data is organized in this CSV file.
CSV stands for "comma-separated values", it doesn't indicate what is in the files.
Open one of your files as a text file and check how the information is stored in there.
If this is a [Nchannels x Ntime] or [Ntime x Nchannels] matrix, with possibly a column header, you should be able to find ways to read it in Brainstorm by selecting the file format "EEG: ASCII text" and then trying different options.
If you have extra columns that are not EMG recordings, you might need to delete them from the csv file first (with Excel or OpenOffice for instance).
A simpler solution would be to use your acquisition software to export the recordings in a standard file format such as EDF, if possible.