It's getting a bit late for recruitment this year, the usual time is Jan to May, though there are some jobs that come up later. You seem to have found the relevant places to look for jobs, it's a case of look on a regular basis during the recruiting season.
I found this one: http://www.antarctica.gov.au/jobs/jo...ground-support
with the Australians, not sure if it is particularly relevant or if you interested in this?
There's also regular flights in the summer months by British Antarctic Survey, a Chilean civilian company and private companies here: http://www.antarctic-logistics.com/index.html
and here: http://www.white-desert.com/
While jobs are advertised directly, it can't hurt to contact them in advance and find out what their recruitment procedures are for when jobs come up.