I have a three way switch on a fixture and want to replace the switch with a timer / switch. The only timers that I saw were for regular switches not three way switches. Short of going out and finding a timer for a three way switch, is there any way to install the regular timer, by converting the switch to a regular switch since I really do not care to have a three way switch?

Here is a diagram to look at: Three way switch description

Remove one of the wires on A or B and put a wirenut on it.
Put the remaining two wires on the timer.
If it doesn't work, toggle the other switch.

If the position of the other switch doesn't correspond to UP=ON, then cap off B if you used A or cap off A if you used B. The other switch can be used as an enable.

You could have 3 way AND timer. One of the 3 way switches goes to light. That will go to timer as well as a hot from the other three way. Your timer will override the 3 ways. To turn off, a three way would have to switch off as well as timer/switch expired or off.