Most BCD thumbwheel switches I have worked with have 5 connections. The first is the common connection and the other four are the 1, 2, 4, and 8 outputs. It sounds to me like you have the common connected to the +5 volts of your system. Now what you need to do is connect a resistor between the 1 output and ground, the 2 output and ground and so forth for a total of four resistors.

If you have more than one thumbwheel switch a resistor array will probably be easier to use. Resistor arrays have several resistors connected together with one common terminal. The value of the resistors can be anywhere from 2.2kohm upto perhaps 47kohm depending upon the datasheet of the 245 you are using and the distance to the thumbwheel switch. If you have the common connection of the thumbwheel switch connected to ground you will need to connect the other end of the resistors to +5v. I hope this helps.