This definitely isn't a hack. Mass Effect 2 is a role-playing game. The choices you make determine whether you live or die at the end.
Someone close this please.
How to Survive the Final Suicide Mission in ME 2 - Guaranteed Solution *SPOILERS*
Here's one way to get all the team surviving the suicide mission to get the best ending.
1. Every crew member must have a loyal status - If you have arguing crew members such as Jack then you will need max renegade or Paragon to return them to loyal status.
2. You must have researched every upgrade for your ship (offensive+defensive upgrades only)
3. Complete all side missions and all resource gathering you want to do BEFORE starting the IFF quest - the IFF quest is story critical and can't be missed. It's the mission where you enter the derelict reaper craft to retrieve it.
4. Complete IFF quest, after completion the only thing you should do is Legion's Loyalty quest if you start running around doing other quests your non party crew begin to die.
5. After Legion's loyalty quest, pick the option to immediately go after the crew.
6. Send your crew members as follows:
Tali in vents
Garrus leading first secondary squad
Jack Biotic barrier specialist
Grunt - chose option to escort crew back
Miranda leading second secondary squad
Choose whatever you like for the last team. Choose option for team to rear guard
After doing everything listed here, you should get the full, complete, EVERYONE survives ending (including non-party-members). The achievement will pop up after you've spoken to the illusive man once it's all over.
Obviously this is not the only way to do it, but it should guarantee success.
If you do this without saving the Normandy Crew Members, Mordin or whoever dies.