I've been making my girlfriend squirt for months now and let me just say this. Yes it can be done and for me it's a massive turn on. People have touched upon the subject in here, but I will try to go into a bit more detail on it.
Do whatever you know makes you feel good. If you love oral, get him to do oral. If you like it when he uses his fingers, do that. It's essential to be turned on, I mean really turned on.
Now I've never been able to make my girlfriend squirt during sex, however I have been very successful when fingering. The main thing you have to do is stimulate the G-spot. This can be found by inserting your fingers to about the second knuckle and curing your fingers upwards to the roof. You can stimulate that in many ways by rubbing it, tapping it or using techniques like twiddling your fingers back and forth.
When I first did this, it had to be done a lot before I got to see the results. But here is the technique I usually use. Quick finering with 2 fingers can make a girl squirt, but to really get her going, (if you're able to) change to 3 fingers. The change in gurth (or however it's spelt) really makes a huge difference. I mean huge.
Obviously this will vary from person to person but this has been working for me for months now and I have to say, I've never tired of doing this ;) So I hope you can achieve what you're trying to do! Good luck! :D