Using Flash 8, and ActionScript 2, what is the max value that an _x property on a MovieClip can be? For instance, is it okay to position a movieclip at _x = 60000?
I think limitations will come from the dimensions of your clip, not as much from the position. The limit is 2880x2880 size wise, and I there might not be one for positioning, but even if, 60000 px should work. I tried creating and empty clip, positioning it and tracing it. Something as simple as that works.
What exactly are trying to test/achieve ? This sounds a bit like a workaround, maybe it can be avoided.
To answer your question, as far as i know, you can set the ._x property of a movieclip to any value you want as long as it is within the boundaries for of a (32 bit) Integer.
Setting the property to extreme high values will effectively hide the movieclip as it will sit far outside the boundaries of the stage.
Of course setting ._visible to false is a much cleaner way to achieve the same thing.
On my system here (Intel 6300), a quick code test produced a +/- limit of 107374182 on the _x and _y properties.
I assume this may change depending on the hardware running the player.