Little One NEEDS some FLUIDS to keep from becoming Dehydrated.

Since you don't have the KMR yet, plain ole Water is better than no fluids.

Use a dropper, a syringe, or in a real pinch - a drinking straw to
get
the fluid into his mouth.

Straw method -
Put water in a glass;
Put Straw into glass;
SEAL the top of the straw with a finger;
Pull out straw (KEEPING finger on the end);
and "insert" straw into the side (cheek area) of his mouth;
Release the seal made by your finger...
the inch or two of water trapped in the straw will run into his mouth.

Close his mouth and rub his throat ... he'll swallow.