How to flash:
1. First, reboot into recovery via 3-button-combo, ADB, terminal, w/e.
2. Partition SDcard (swap: 0, ext: 512), ext2-ext3, then ext3-ext4 it.
3. Wipe data (data,cache,dalvik-cache,ext).
4. Connect the device to PC, copy Megatron over to the SDcard, disconnect.
5. Flash it via "flash zip from sdcard"
6. Reboot
Source: xda-developers.com Megatron-v1 Thread.
The steps provided above will be needed to be done for you to flash a new Rom. The 4th step refers to the Megatron Rom, but just put whatever Rom you're planning on using in its place.