From the GSX manual, Page 11:
NOTE: You are supposed to operate the Jetway. GSX doesn’t control, changes or add anything regarding the standard Jetway operations in FSX. A default airport or an airport that has proper FSX jetways will continue to work in the same way even with GSX. If the scenery you use has other means to open Jetways (like using COM frequencies or other additional programs), you will continue to use that method to operate the Jetway, GSX won’t interfere or interact with it.
In other words, nothing about jetways operations on a specific scenery will change after installing GSX. They will still operate (or not) as they used to be before installing GSX, which means:
1) With CTRL+J if the scenery supports the standard FSX method of animating jetways. All FSX default sceneries, all FSDT sceneries and some sceneries from Flightbeam and UK2000 supports this method.
2) With some kind of custom control (like COM frequencies) if the scenery use its own method of animating jetways. This was a (relatively) popular method, especially in FS9.
3) They will remain static as they were before installing GSX, if the scenery doesn't feature animated jetways at all.
