There isn't native support for that, but the relevant information that associates things with a given google account is in the ~/.skicka.metadata.cache and ~/.skicka.tokencache.json files.
So, if you are logged into one google account and want to access the Drive account of another one, move those two files aside, log into the account in your browser, and then run skicka. When you authenticate in the browser, corresponding files for the second account will be created.
Later, to switch back and forth, just swap the corresponding versions of those two files.
Matt