Help me out here Barb.
The Winegard Entertainment Select is a bunch of push button switches, or am I missing something?
The dash radio may have an iPod cable attached to it. Some Winnebago's came supplied with a cable. Depending on your brand and model of dash radio there may be a "DIN" type plug on the back. There is a special cable made for those for the iPod and Sirius connectivity. The only way to tell is to look at the OEM manual, or pull the radio out and see what you see.
If you have an entertainment system that is part of the "house" system, contains an am/fm receiver, DVD player, etc., there should be at least a right and left (white & red) RCA phono jack on the back side. Some may even have them on the front side for "quick" hook-ups, while the back is more for permanent hook-ups. Any 3.5mm plug that will plug into the iPod and has a set of RCA cable on the other end should work. You will have to tune the entertainment system (Mode switch) to the AUX input mode. It depends on the functionality of the entertainment system.
Also on the market, and I have one that I use, is a Belkin Model #F8Z049-BLK
FM Transmitter and Doc. It plugs into the cigarette lighter. It works well for me, although I have not used it for a long time because i have an AUX input on my dash radio.
On the iPod to RCA cable there will be two varieties. On is the 3.5mm stereo plug type that splits the audio to the two RCA plugs, and the other will be the one that plugs into the charging circuit and splits into the RCA phono plug.
The better method would be to see if there is an adapter port on the dash radio. It will then take care of all the needs including charging, as will the Belkin FM Transmitter I mentioned.