Well, if you know your way through some actionscript code you should be able to make the preloaders invisible. They are not static animations on the screen though, but created with actionscript so you would have to location the exact code and set movieClip._visible = false; or something.
Just before you edit the FLA source files, be aware of this:
viewtopic.php?t=4233
The preloaders only display on the SIDE of the image if the visitor has clicked to go to another menu or another image. If not, the preloaders are not visible. Honestly, I have not heard a complaint of this before ... On the contrary - Some visitors will get very agitated if they click "NEXT" and nothing happens ... Maybe they think there is something wrong with gallery, or it is the last image. Thats the whole point of a preloader, to assure the visitor "please hang on while we are loading what you just clicked". On top of that, Imagevue has some of the most subtle preloaders you can find ... I personally dont think your client is seeing the bigger picture here by denying industry-standard methology.