It actually wasn't that difficult. I was quite intimidated by the process until I played around with it for a day or two. You can set up an account and have a book completely ready to publish without any obligation to do so. So take some time and play around with it.
With City Folk, I used Photoshop and Microsoft Word. I made all my strips the same width and placed them evenly apart in a word document. I added page numbers and chapter headers and whatever else I felt like. Once my Word document was ready, I converted it to a PDF (lots of tutorials on that online, it's quite simple) and uploaded it to Lulu.com.
From there you can set a price and upload a cover. My cover and back cover are two different images that I worked on with Photoshop. The spine was a default that they provide.
Make sure when you start this process to know what kind of book you want. How tall do you want it? How many pages? Black and White? Or Color? They give you a lot of options. My production price for the book was around $8. You always want to sell for double that cost.
If you have any other questions let me know!
Ryan.