Divine metamagic applies only to divine spells, IIRC (may or may not be an issue in the hands of a DM, who has more leeway in interpreting the rules creatively).
Though I find the cr+2 adjustment for a lich somewhat high, and feel that I would be better off tacking on the necropilitan template instead. I still get most of the goodies that come with the undead type, and have 2 more class lvs to play around.
Alternatively, throw on class lvs onto an existing undead monster (like a mummy cleric or ghast wizard), though you must bear in mind that those class lvs do not automatically get upgraded to d12s, so your undead caster may have much fewer hp than expected.
Though I find the cr+2 adjustment for a lich somewhat high, and feel that I would be better off tacking on the necropilitan template instead. I still get most of the goodies that come with the undead type, and have 2 more class lvs to play around.
Alternatively, throw on class lvs onto an existing undead monster (like a mummy cleric or ghast wizard), though you must bear in mind that those class lvs do not automatically get upgraded to d12s, so your undead caster may have much fewer hp than expected.