Wicket is buildable only using maven. Using maven install is not bad if you have to just build Wicket once, but when you have to build it multiple times, its takes its toll :) - on my 2.4GHz, 4Gb RAM dell laptop it takes atleast 8-12 mins - thats painful.
If you are not Maven guru and would like to get this done quickly - here is what I tried and it worked. I could not find any documentation that shows exactly these steps so...
Depending on the wicket jar that you want to build - cd to that subdirectory under wicket and use
mvn -Dmaven.test.skip=true compile jar:jar install:install
or any combination of the options above which are self explanatory, but I will explain them anyway, just in case-
compile - compile phase of maven which will compile all
jar:jar - is the jar goal of package phase if you specify the package instead of jar:jar it will also try to generate javadocs which will take forever
install:install - deploy phase goal
Hope that helped - would save atleast 30-45 mins if you didnt know maven