It is possible to take courses during the summer without having been admitted to the University of Hawaiʻi at Mānoa. Application materials are usually available in mid-March on the Outreach College Summer Session homepage: http://www.outreach.hawaii.edu/summer/default.asp
It is not possible to pursue an MA in SLS by taking summer courses only. Admission to Summer Session does not constitute admission to the University of Hawaiʻi at Mānoa.
The Department of SLS offers a small number of courses in the summer. A list of courses may be found on the Class Availability page: https://www.sis.hawaii.edu/uhdad/avail.classes?i=MAN
Current students may also find relevant elective courses offered by other departments.