1. voltage divide your dc source to 0.5 volts. If 5 VDC source 9k and 1k resistors.
2. voltage divide your 0-5 volts source down to 0-3 with a 2k and a 3k resistor.
3. add the two voltages for a 0.5 to 3.5 VDC output signal that track linearly with the 0-5 volt source.
4. apply both signals to the inverting input of the OPAMP through a 10k resistor. That is one 10k resistor for each source's output joined to the inverting input.
5. the non-inverting input goes to ground perhaps thru a 1k resistor.
6. the feedback resistor is 10k.
7. Oh yeah, and then invert the negative 0.5 to 3.5V signal.
8. Connect the output of the 1st OPAMP to another OPAMP's inverting input thru a 10k resistor. 10k feedback resistor. 1k from ground to the noninverting input(optional). The output will be 0.5 to 3.5 volts.<p>Nine (or 11) resistors and 2 OPAMPS and + and - 5 VDC sources one each for the OPAMPS. Yikes, there has to be a better way. I'm looking at what Dale and Al said again. This is spiralling out of control, but it will work.

-Rick