Yep.. just get a thin laceweight mohair and knit with two strands (your regular yarn and the mohair) together. It might not even affect the gauge, but you should do a gauge swatch anyway to be sure. If you use a thicker mohair, it will alter the gauge significantly. You can do this of course, but check that gauge.
When you're finished knitting, follow the laundering instructions for the more delicate yarn (probably the mohair). You can fluff the mohair up to bring out the halo by brushing *gently* with a bristle brush.