How can i change the icons of Sony Ericsson G900 without installing any software on my phone.?

Or if required any software to be installed on my phone.How can i do the permanent hacking so i can remove the software afterwords any doesn't require any software to be installed on my phone.Changing my icons means that when i see the themes for Sony Ericsson G900 on some websites it contains icons along with visual styles son when i download and apply on my phone the visual style is changed but icons cannot.So please help me.Tanks.|||You're gonna have to check the forums for that phone. Just google ur type of phone then search for forums. I thought I knew but it was the wrong phone, or check youtube.