There are two official guides, the first one is at http://siremis.asipto.com/install/ and, by my opinion, it is not good, probably writed for previous version of the Siremis and kamailio...following described steps is unable to install siremis version 2 with kamailio 3.1.x (six hour of troubleshooting).
Another manual is at http://kb.asipto.com/siremis:install20:main, and it looks good.