Asymptotes in 2D plots



Hello Fellows,

I'm currently using Maxima 5.9.0.1cvs and was wondering whether I can have 
asymptotes be shown in 2D plots somehow? I've checked the archives, google 
and the documentation but was unable to find something on whether it is 
possible or not.

If Maxima or the different plotting software provide this feature, I would 
appreciate any help on how to enable / use it.

Thanks in advance,

~stefan