Hi Moroianu,
In general it's not possible to open the select dialog window through javascript function. This kind of scenarios is not supported by all browsers. Since you would like to open this dialog through button click event, why don't you use the existing select button and just change it's name to "Load Photos".
In order to change the text use the following property Localization-Select="Load Photos".
Kind regards,
Dimitar Terziev
the Telerik team