Mince the chives as finely as possible.

Place in a jar with the oil, and let sit for one day before using. Over time, the chives will infuse the oil even further.

Refrigerate and use within one week. Strain the chives out at any point, or not at all. It's completely up to you. I tend to leave them in and add the chives and oil to vinaigrettes, salads, and roasted vegetables and legumes all week.