If you wish to feed properly, then this is an in-depth guide on feeding with perfection. The guide not only reveals how to feed correctly with Master Yi, but shows how to turn the tide in the favor of the enemy team.

Master Yi excels at feeding.
Master Yi is the most agile champion in the game.
Impossible to chase when used correctly.
Super Speed!
Super Feed!

Game will end super fast.
Besides that there doesn't seem to be any other cons.

For runes I take movement speed quintessences for super speed. These not only help me feed, but also give me an edge early game for catching enemies.

For marks I take attack speed so I get super attack speed too. Helps me kill, yes you are supposed to get kills too in order to finish your build. You can take flat cdr so you can use your ultimate more often.

For glyphs I take attack speed for faster attack. You take cdr if you black.

For seals I take attack speed yes?

In order to have optimal revive time I take 1 point in preservation on the defense tree. Caution: This section is extremely important!
You want to make sure you max good hands on the utility tree so you can spawn faster and thus feed faster. You want to make sure you don't add any points to awareness on the utility tree because then you will level fast and that means longer death timers so slower feeding. The rest of the points go in the offense so you can feed but kill at the same time so you can finish build.

The best spells for super feed are: revive and teleport, as these allow you to cover the most distance. An alternative to teleport is Ghost, but I prefer teleport.
Other viable spells are:
Smite ( If you plan on jungle feeding/jungling)
Clairvoyance (to ensure they get early first blood)

For items I start with boots of speed. After I'm done feeding I come back and buy boots of mobility as these boots get you the fastest speed. I then build 5 zeals, starting with the dagger first for super attack speed. After that I turn my zeals into phantom dancers. Remember this build is expensive so feed, but also get some kills.

I take 1 point in Alpha Strike at level 1 because it is yi's main source of damage early on and it is a ranged attack. I max Alpha strike first, then max Wuju Style over meditate because Wuju Style gives you the attack damage you need with your super speed attacks and meditate is just going to heal you, making it harder to feed. I max Meditate last and make sure to take points in Highlanger when possible.

In team fights Master Yi truly shines.
I try to initiate every fight by running in to the enemy team and attacking the weakest looking enemy. I start by using Alpha Strike and then activating Wuju Style and auto attacking the target as he is fleeing. I also try to use Highlander when it is up in order to become Super Yi. The goal here is to die as fast as you can preferably go into a 1v5 and have all the enemies blow their CC and Ultimates on you while killing your target in the process and making it easier for your team.
Also, if you die you can just use revive and with the items+ revive you should be able to rush back into the fight again for a quick feed.

This build excels in Ranked Play because the enemy team will not expect it. The goal is to feed hard enough to get them to be cocky and fall to your team. Also try to initiate every fight and take all their CC/Ultimates; then just revive and join the fight again.
However, if your team is giving you a hard time, then just do some hardcore feeding and they will eventually stop and see how useful you are to them.

I'll try to post some of my previous match results as soon as I can.

Start by taking a cloth armor and 3 health pots. Head to the blue buff and attempt to solo it. When you die just revive and try again until you can kill it. At this point you should be significantly under leveled so, you look for a lane that needs feeding and rush to feed whoever you have targeted. Try to do this every time you get either blue or red buff.

Alpha Strike frequently and just auto attack the minions. Try to get last hits or farm near the enemy towers.

Here is a video of someone playing Master Yi correctly:
http://www.youtube.com/watch?v=CWbFXmBmgqs&

In perspective, you want to feed fast and hard while getting a few kills, but the main goal is to have fun!