i personaly think you should invest in the guide,amigo. i HAVE the guide and still found it nigh imposible to get that one:rolleyes2 . but it is worth it. your best bet is to use the commspheres (C4) multiple times in ALL,yes all, locations after;

1) before talking to buddy,

2) after talking to Paine,and

3) after Tobly mission.

Good Luck!!!!!!!!!!!!!!!!