Later on in training when you do more than one leg at a time things get easier but the legs can be done on their own.
As has been mentioned leg 1 is easy - start at Keswick and jog back on the old railway track after Blencathra or catch the bus from Threlkeld.
Leg 5 is easy if you start from Little Town and go to Honister and back. The road bit can be run out and back on its own if you wish for route finding or just driving it.
Leg 2 is more tricky but I would start at Dunmail Raise and go to Threkeld. Walk/jog or catch bus back to Keswick. Options then are: bus/hitch back to car that day or stay the night in Keswick leaving the option of reversing the route the next day and picking up car.
Leg 4 is very feasble to do coming back on moses trod or if this is too much then just drop back down into Wasdale from wherever you get to eg Blacksail or Kirkfell.
As already mentioned leg 3 is the hardest but you can do an out and back from either end, go for the hitching back to car option or if you can afford the luxury then book a night in a b and b in Wasdale and walk back to your car at Dunmail the next day.

You might be interested in my experiences on wightplodder.blogspot.com
It has links to swisstoni and fellshoeshuffler excellent blogs as well.