ActionScript 3.0, SEPY Editor, and Compiling w/ MTASC... Problems

I’m trying to use the SEPY editor to compile an *.AS file into an SWF file and I think the editor thinks my ActionScript code is 2.0 vs. 3.0. The reason I think this is due to how it seems to be bombing on the “Package” reserved word. Has anyone on here ever used SEPY to compile an *.SWF file? If so, how did you do it? What were your configurations, etc., etc.? If not, would you happen to know of any open source / free apps that can take an *.AS file and compile it into an *.SWF file?

I found that FlashDevelop has everything I need. :.)