Get Certificate
1. Try to open up a secure site that you are planning to test
2. When Security Alert pops up, click View Certificate. If there is no security alert, just double-click on the lock icon that indicates that the site is SSL-secured
3. Click Details, click Copy to File
4. Select format (like base-64, ...)
5. Save the certificate

Add Certificate:
Run the following command in DOS (for example):
set JAVA_HOME=c:\jdk1.3

%JAVA_HOME%\bin\keytool -import -alias your_alias -file cert_name.cer -keystore %JAVA_HOME%\jre\lib\security\cacerts