Gene Targeting using single stranded oligonucleotides

[blazinfury]

I was recently reading about the mechanism of gene targeting using single-stranded oligonucleotides. I am familiar with the targeting using TALENs, ZFNs, CRISPR, etc, but my issue is with understanding the mechanism. With the latter targeting technologies, they bind to a particular locus, induce a break and then with a donor plasmid, one can promote repair. However, how does a single stranded oligo induce targeting? Is a particular enzyme or something to that effect added when transfection occurs?