my situation is the opposite of yours. i had to travel for work whilst she was here in SG.
What i did was this:
Get dry ice & a styrofoam box. I use millk bags when i'm overseas and put them into a zip lock bag. line the styrofoam box with dry ice and then put the bags of ziplock bags into the box. then cover the top with dry ice. Seal and pack into my check in luggage.
And this works pretty well. My journey end to end was about 10 hours and when i unpacked, it was still unfrozen. If you buy the dry ice from a wholesaler, based on the estimated amount of milk, he/she might be able to give you an indicative amount of dry ice required to last the duration of the journey. for me, i bought my dry ice from haagan daaz and had to 'guess-timate'
as for transportation, i believe if you are going in and out, you can handcarry through the customs. if you are not, i believe DHL does do special handling of dry ice shipments but price wise i think ull need to check, ive lost touch