Already done. Threw together an initial translation in 2001, concentrating on translation and syllable matching but not rhyming anything.
Reckoned if any language had a translation for "Mama, I killed a man, Put a gun against his head, pulled my trigger. Now he's dead." Klingon would.
It's published on the net, but I reckon it's rather rough. I may consider returning to it and cleaning it up.
As slashdotting my own site ain't too brilliant an idea I'll not provide a direct link, but include some of it below.
Ahem:
teH'a' yInvam pagh
tojbogh pa'Daq jIHtaH'a'
mujon pumbogh puH
ghu'vam vItvo' vIHaw'laHbe'
mInDu'lIj poSmoH
chalDaq yInuD 'ej yIlegh
loDHom mIpHa' jIH, chovup vIneHbe'mo'
jIpo' 'ej nom jIvIHlaH
HoSchugh SuS pagh pujchugh SuS
chay' HoS SuS? vISaHbe'! jIHvaD SuS HoS vISaHbe'law'
-jIHvaD
SoSoy. qen loD vIchotpu'
nachDajDaq HIch (vI)vIHmoHpu'
chu'wI' chu'chu'pu', DaH Heghpu'.
SoSoy. qen taghpu' yInwIj
'ach DaH yInwIj naQ vIpolHa'chu'pu'
...
tlhoy paS, pawlI' HeghwIj
jIHeghvIpmo', bIr pIpwIj
DaHjaj 'oy'law'taH porghwIj
...
jIHvaD veqlarghHom poltaH veqlargh 'e' vISov
...
jIHaw'nIS neH - naDevvo' jIHaw'nISchu' neH
pagh vISaH 'e' vItu'
'e' leghlaH vay'
pagh vISaH 'e' vItu'. jIHvaD, pagh vISaH 'e' vItu'