The old days of installing custom ROM on Android involves manual unlocking of the bootloader if its locked and rooting via flashing insecure kernel. Now, custom ROM like from CyanogenMod is just one app download away. CyanogenMod just released their CM installer at PlayStore along with a desktop client. The desktop client is only available for Windows 7/8, sorry Mac and Linux. No word yet for other OS, in the meantime the mobile app is promising.