The usage message just says what it does support - a single session definition: [-ss SESSION], compare to --files for example of an option accepting multiple inputs: --files [FILES [FILES ...]]
But your heuristic (in infotoids) could deduce session identifier for every accession, so if the path you pointed has multiple accessions, it could assign corresponding multiple/different sessions to each accession it is to process. See e.g. ReproIn heuristic – we are typically assigning session identifier to the scout scan. It also supports _ses-{date} and _ses+ identifiers so session would either correspond to the date (used for our QA phantom scans) or just incremented each time correspondingly.
Hope this helps