Heres a verified working procedure for installing DAViCal on Debian GNU/Linux Etch as of this writing. As indicated at the link above, youll need to add a new source for apt. (Feel free to use sudo if it suites you.)
Read more here
The installation documentation is somewhat correct for 0.9.6.1. Actually, including the wiki, I count no less than four guides for handling installation of DAViCal. None of them are completely right. Scary, no?