I would say it's pretty easy if you are technically inclined. When I implemented the first iteration of my text search engine using Lucene, I didn't even know

I would say it's pretty easy if you are technically inclined. When I implemented the first iteration of my text search engine using Lucene, I didn't even know Java but I was able to write my own custom tokenizer and get it to index and retrieve results from the index in about 6 hours. I highly recommend you get the book "Lucene in action" as it gives solid examples that you can build upon.