Updating 3DS to specific firmware

I just picked up a 3DS and I've got a AceKard 2i on order. I'm trying to upgrade the system to a specific firmware instead of the latest. Is that possible or do I have to upgrade to 1.4.2 and wait for the cart's to catch up?

you cannot update to a specific version. You can either update to the latest, or not update at all until the carts have an update. If you do not have a DS lite then waiting is the safest bet because the cart updates may need a non-updated console to run the update on.