I don't know about colour negative film but unexposed slide film works once developed. Slide film needs to be transparent to IR by necessity, otherwise it could be damaged by the heat from a projector bulb.

There's no guarantee your film will work and unless you can develop colour film yourself, a cheap IR filter from an auction site may work out cheaper (and work better) than paying for your film to be processed. I've got 720nm and 950nm IR filters for use with my modified Olympus C5060, both are Chinese no-brand filters that cost very little and they both work very well.

Incidentally, you don't want to invest in expensive filters until you know the IR characteristics of your lens. Some lenses (on both fixed lens and dSLR/system cameras) show a "hotspot", an area in the centre that is lighter and has reduced contrast. My Oly C5060 doesn't have this issue but my old Minolta Dimage7 definitely does. This issue can affect both digital and film alike as it's down the lens design and not the imaging technology.