Feminisation is the change from a male dominated or mixed gender workforce to a female dominated workforce.  Proletarianisation is the degradation of: "old" professions; "old" trades; "traditional" labour; or, new work with a high degree of worker control: to management controlled execution of duties as standardised labour (its a bit more complex, but...).

Proletarianisation and feminisation go hand in hand.  The women we see working for pay on _Mad Men_ are primarily secretaries.  As Margery Davies shows in _A Woman's Place is at the typewriter_ [http://muse.jhu.edu/books/9781439905821?auth=0], secretarial duties were once performed by autonomous men with generalised duties.  Davies finds in the late 19th century that the combination of employer's views of women as "docile" and "cheap" combined with scientific management which "deskilled" (Harry Braverman) the duties performed resulted in a rapid feminisation of the workplace.

Much like Engels shows that "women as homemaker" is historically contingent, and can change rapidly within a generation as pay changes gendered status, so too does Davies show that secretarial duties' gender position is contingent on the organisation of the workplace.

As far as secretarial duties requiring uneducated labour, IIRC secretarial schools were widespread, and most secretaries were expert business machine operators from tabulators, collators, type writers, telephones, etc.; and the social construction of required duties ranged from trivial to broad ranging.  In comparison to equivalent male occupations, skilled machine operation was considered from unskilled through to trade.  I would suggest that judged against a male hierarchy of skill, the women portrayed in _Mad Men_ working secretarial work are between unskilled and trade skilled, with one exception of a generalised autonomous worker who occupies a managerial role.  Whether we ought to criticise the presence of a unique skill scale for female office work which degraded highly skilled or trade machine operators to "unskilled" work in financial and social respect terms is a political or moral question; but, the presence of different skill hierarchies in farm, industrial or office work all of which were gendered ought to raise the question of whether skill hierarchies actually existed or whether they were cover for a gendered or industry based division of labour.