Don't boil, it will set the pectins.
There are two simple methods you can use. Do both if you are really concerned:
1) Freeze the fruit, and add it straight to the beer. freezing will kill most bacteria, and the alcohol in the beer will inhibit the rest. Freezing also breaks down the cell walls so the yeast can get at the sugars.
2) Chop or mash the fruit (do this so the sacc can get to the juice). Add a little water to cover. Heat to 145 F and hold for 20 minutes. Try not to go much higher to prevent pectin setting in. 20 minutes at 145 will pasteurize the fruit. If you overshoot and get close to 160 F, take it off the heat immediately to prevent it going higher. 5 seconds at 160 F is sufficient to pasteurize.
I'm not sure what temperature sets Pectin. I think it is above 160 F. But if you aim for 160 you could easily overshoot by 10 or more degrees if you are not careful.