"Liquid Sand Paper" is a diluted form of the solvent used in gloss paints in the first place, Diethylene glycol monobutyl ether (DEG monobutyl ether). It also contains fine grains of silica (quartz) in suspension. It works by slightly dissolving the surface of the gloss paint and allowing the silica grains to embed themselves in it, which then allows the next layer of paint to adhere.
If you try to volatilize (spray) it, you would not only need high pressure to avoid having the silica clog things up, but it then becomes HIGHLY dangerous to inhale.
Don't try it, that's not what it was designed for.