You will need a hot water line and a drain line back to the sink. The shut off valve on the hot water supply line under the sink can be changed with one that has another outlet. One would again go to the sink faucet and the other to the dishwasher. You can purchase stainless lines that would attach to the dishwasher and the shut off valve. You can join these supply lines with a compression fitting if you need extra length. The drain line would attach to the disposal. Make sure you punch out the plug in the disposal.

Many portable dishwashers are designed so that the can be converted to a built-in model at a later date. If yours is one of those, refer to the owners manual for instructions on how to make the conversion.

Otherwise, you simply need to replace the single-outlet hot water supply valve under the sink with one that has two outlet connections. Click on the link below to see an example. Your local hardware store should be able to readily supply you with whatever you need.

Here is a link that might be useful: {{!gwi}}

You don't need to replace the valve, just this tee which screws to the valve and adds a second 3/8" connection. Available at any big box home improvement store.

Here is a link that might be useful: Add-A-Tee