Depends on the logic you want to use to seed the athletes. If its based on past performance (and no other criteria), then the process is pretty straight forward. You enter the overall times and sort and you have your seeds.
If other criteria is involved - then the seeding might be a bit more complex. Let us know what criteria you intend to apply and we can help.
As for the competition, I would split it up based on two things (in terms of hierarchy):
Total <- Individual event
For each event, you can determine who has won based on times (presumably), which then equates to (I am assuming) points. That will then give you the total points for each competitor for all three events.
A simple formula or even a sort after the events will give you the winner.