Format: 

Lastname, Firstname, ed. Title of Conference. Venue, City, Month Day Year. Publisher, Day Month Year. Database Name or Title of Non-Publisher Website, DOI or URL.

Lastname, Firstname, ed. Title of Conference. Venue, City, Month Day Year. Publisher, Day Month Year, URL or DOI (when accessed from the publisher's website).

Lastname, Firstname, ed. Title of Conference. Venue, City, Month Day Year. Publisher, Day Month Year.

Examples: 

IEEE Conference on Technologies for Sustainability (SusTech 2013). DoubleTree by Hilton Portland, Aug. 2013. IEEE, 2013. IEEE Xplore, doi:10.1109/SusTech.2013.6617290.

In-text: (IEEE Conference 6)

Notes: 

You should include pertinent information about the conference such as the location and dates immediately following the title of the conference unless this information is already included in the conference title (MLA 50). If the publisher is also the corporate author (e.g. IEEE), omit the author and list the organization in the publisher field (MLA 25). For instances where you do not include an author or an editor, only include the first word noun phrase (noun and any preceding adjectives) of the conference title in the in-text citation as above (MLA 118).

Source:

This source type is not covered by the MLA Handbook (8th ed.)