avisynth how to merge two mono channels into stereo?

[smok3]

i would want to do something like:

vid = somesource(file.avi)
a1 = wavsource(file.a1.wav) # mono pcm file
a2 = wavsource(file.a2.wav) # mono pcm file
stereo = constructStereo(a1,a2) # <-how?
audiodub(vid, stereo)

how?
:thanks:

p.s. this is just to construct playback, if there is another option using mplayer for example, that would be even better (piping from sox to mplayer was a failure on win xp).

[Kurtnoise]

stereo = MergeChannels(a1, a2)
return AudioDub(vid, stereo)

[smok3]

thanks (and shame on me...).