GET, bookmarkable searches, and forms

[eluser]snifty[/eluser]
I'm sorry, I know this is discussed elsewhere in this forum (and also on Stackoverflow and various blog posts), but I have not been able to wrap my head around a solution for my particular situation. I'm going to describe what I'm trying to do and hope someone will take pity here and give me some pointers...

Example:

http://tangorin.com/general/

This is a Japanese dictionary site. If I type a word in the big input at the top, like "sushi" and press enter, I am sent to

http://tangorin.com/general/sushi

This seems to me to be an obvious thing to want to do -- for one thing, the link is bookmarkable. I'm also building a dictionary and bookmarkability is crucial. This sort of thing:


http://tangorin.com/general/14324DCAF3EDA

...won't cut it in this instance.

Now, surely this is possible, presumably through the use of routing, but I swear I can't figure out how to do that in CI. Any pointers would really be appreciated, thanks.