If you're very VERY careful you can do it with a brass rod or a solid piece of delrin/ABS/or nylon. A bit of lube in the dovetail, wait an hour, then start tapping. Use some masking tape to outline where you start so you know how far you've moved.
Otherwise you'll need a sight pusher tool. You can find them on e-bay or wait a bit for the made in Canada one to show up.
BTW what kind of ammo are you using ? It's possible that moving to a different load can help. Also if the gun is new to you, you might want to wait a bit before modding it much. Depending on whether you have a high mount beaver tail or not, that can change your point of impact significantly, as well as grip thickness and trigger length.
gl