I guess 'uigetfile' or 'uigetdir' cannot be customised programmatically, one possible workaround would be to customise the dialogbox by running it through commandline. Later, it will pop-up the same whenever a call to it is made again. If you want to filter the files that are displayed, you can specify the supported types at the time of creation.
Refer to the following documentation:
Hope this helps!
