First download the website’s certificate from Firefox:
View Page Info > Security > View Certificate > Details > Export >
...\jre1.6.0_33\lib\security\website.crt
Then generate the keystore:
$ cd ...\jre1.6.0_33
$ bin\keytool.exe -noprompt -import -keystore website.keystore -alias website -file lib\security\website.crt
Enter keystore password:
Re-enter new password:
Certificate was added to keystore