OK I'll try and explain the old mouth grunt to you. This only works if you've spotted a group of Javalina and they are in ear shot AND you are down wind. A javalina can't see very good but brother they do have a good nose.
So here goes
make a gentle cough it should sound like UHh UHh and push the H with your diaphram real quite though no louder than an indoor voice. This is the sound that Javalina will make when they meet each other and are freindly. If they don't have your wind by golly they'll come into you and I mean right into you and start a nice little pigalina conversation.
If you can find a recording of these things talking to each other it would help as it's a real simple noise to make and it really works well.