Here is the poem's translation done by blotty and dec. I simply corrected spelling errors. Give all your props to the former two, I just did what Word could have done.
Kallen's Poem:
Extolling the brave chivalry of youth until I met you, I was only merely plastered with thorns. I wanted to change this truth. I seethingly and recklessly made my move. But then, I didn’t believe that anything would come out of it.
When my brother was gone, I heard the sound of the heavy doors closing behind my back. I cannot allow it. I will fight to the bitter end. I decided that I will not go back. Then, someday, I will die like my brother. Until the very end, Kouzuki Kallen would not abide by authority. That bit of willpower I was carrying with me, it slipped away from me, and I can feel it faintly. At that time, I envisioned you like the star at the break of dawn, inviting me. If I would think that this is for you, my body would feel light.
Whatever struggles there are, the pain would go away. I would be the first to come rushing to your battlefield, raging like a lioness, crushing your enemies. I would stand being muddied in order to create a path for you. Looking back, it's mysterious. Even though I should have loathed and rebelled against Britannia's tyranny, without knowing it, I personally held devotion only for you.
Lelouch, that parting kiss, even if it was a lie, if you had said, "I love you," I would even follow you to hell. You knew that, didn't you?
It's not like you. You're good at manipulating people just by uttering such words. Really, it's not like you to be kind. Is it because you told me to live? I didn't fall in love with you just because of that kindness.
Source:
This is thanks to dec, for providing it here on AS, and kanalelou for the original scan: