Why are you using C code to replace the functionality of built in capability to LoadRunner?
See web_save_timestamp_param() for the number of milliseconds since Jan 1, 1970.
web_save_timestamp_param("tStamp", LAST );
web_submit_data("explorer",
...
ITEMDATA,
"Name=class", "Value=com.hyperion.tools.cds.explorer.ExplorerView", ENDITEM,
"Name=id", "Value=EV{tStamp}", ENDITEM,
LAST);
if this is your first trip into the Hyperion universe I would heartily suggest you find the most experienced LoadRunner professional available anywhere in the nation to support your efforts. You do not need to be struggling with tool use while at the same time working in one of the more difficult environments for any performance testing tool. Assuming you get someone who has been succesful with Hyperion recently, no matter what your organization spends (even as high as $300 per hour or more) it will be money well spent versus struggling with both tool mechanics and testing of the environment