finding a hot key(s) to run 'Export Selection'

I’m trying to find/create a hot key for ‘Export Selection’ which is in the ‘File’ drop-down menu in Audacity 1.3.14-beta. I’m using Windows XP as an operating system. I have multiple WAV files that I’m converting to MP3 files and would like to speed up the process.

Thanks in advance for your help,

Audacity 1.3.14 has been superseded. The current version is 2.0.0 which you can get here:
Audacity 2.0.1 is due for release soon and includes better hot key support so it’s worth keeping an eye open for its release (you can register at the bottom of this page if you want to be notified when it is released:

In Audacity 2.0.0:
Edit menu > Preferences > Keyboard.
“Export Selection” is the 14th item in the list.
See here for more details about keyboard shortcuts: