Let me revise, I want to mimic binding MWHEELUP to +attack, so as to use less energy while blinking as a celerity fade. I would like to do so by being able to press MOUSE3 and have it use the +attack command only once. I have tried myself, but there seems to be quite a delay when I try to use the +attack command bound to MOUSE1.

Meanwhile I will try DarkFrost's alias.

alias +single "+attack;wait;-attack"
alias -single "-attack"

bind mouse3 +single

I tried it with parasite too, lastinv to bite, and there was no slow down. But I don't really understand the question =]

"Meanwhile"? What are you waiting for exactly? Has your question been answered? Please re-phrase and repost if not.