Birkat haMezuza

14th of Tebet 5770

Before reciting the blessing, the case with the Mezuzah enclosed should be held against the doorpost -- ready to turn the first screw or tap in the first nail. If using glue or foam tape, be prepared to firmly affix the case on the doorpost immediately upon completing the blessing. (Tape that would easily fall off if bumped into is regarded as too temporary to be considered "affixed")

Once the Mezuzah is in position, but before affixing it to the doorpost, the following blessing is recited:
Baruch Ata Ado-nay, Elo-henu Melekh Ha'olam, asher kid'shanu bi'misvo-tav, ve'sivanu leek-bo-a Mezuzah.

(Blessed are You, Lord, our God, King of the Universe, Who sanctified us with His Mitzvot, and commanded us to affix a Mezuzah).

If you are hanging many Mezuzot at the same time, you would say one blessing on the first Mezuzah -usually the front door- and include in that blessing the remaining Mezuzot. In the Mashadi community, however, families have different Minhaguim on this issue. (Ask a rabbi).

A woman can place the Mezuzah and say the blessing by herself. But when other people are present is not customary, for reasons of modesty.
Recommended reading on various subjects: http://www.aish.com/sp/so/80048777.html