Bringing my 1 y.o. cat home for 3 wks to parents' house. Tips/advice to get him comfortable with their cat?

For Christmas this past year I brought my cat home with me while visiting my parents. At first, it looked like my cat and theirs would get along, sniffing one another and purring. Later the first night, though, both of the cats strayed away from one another. I was only home for five days and they never got a chance to become comfortable with one another.

My parents' cat would hiss at my cat whenever they were in the same room. My cat generally gets along with other cats, and doesn't have any major behavioral issues. Since I'll be home for three weeks this time around, I'm wondering if you fellow cat lovers could give me any tips to make my stay, and my parents' cat's time pleasant. HOPING FOR THE TWO CATS TO BEFRIEND EACH OTHER, AND BECOME FRIENDS. :D

Here's a pic of my cat (his name is Togepi): http://i48.tinypic.com/34nrsyw.jpg