[Threshold]

If you're talking about ones found at Las Venturas Airport for example, then no it is not possible, unless you replace the existing booth with another that supports a doorway or entrance of some sort. Other than that, there are plenty of 'automatic' or 'moving door' tutorials found around SA-MP forums and external communities, so just use the search button.

Or... http://lmgtfy.com/?q=sa-mp%20creatin...ving%20objects