Quickstart instructions:
1) Download latest MIUI Rom for N1
2) Download latest working MIUI Rom for Liquid (better if it's the version preceding the N1 one)
3) Open Auto-LiMPoT and select the 2 roms you've just downloaded in the input fields
4) Choose a destination and filename for the rom that will be created
5) Choose the options (they're self-explanatory)
6) Click "Build Rom" and wait ;)