What commands are necessary to allow certain pc's connectivity to a Comcast broadband connection on our ASA5510. It has 3 interfaces. 1 is our inside network. 1 is our outside connection for our Stratus Wave ISP which uses a static IP address and the 3rd is a Comcast connection using a DHCP assigned address. I want certain users on the inside to go out over the Comcast connection for their internet access.
Based on what you are telling you want to have to Internet Providers connected to your ASA and you want some users to go out using one ISP and some other users the other ISP. In other words you are trying to do policy-based routing. Unfortunately the ASA does not have the capability of doing such thing. You can configure the ASA to have a backup ISP and this only works when you have one active ISP and another ISP waiting to come alive in case the primary fails. It uses a concept called route tracking.
If you want to do policy-routing I suggest you using a router.