like all the experts have pointed out using an expodisc or whitecard with your custom setting will yield the most accurate result. Coupled w a calibrated screen and shooting in RAw as a safe guard for more buffer to adjust post processing.
If it is a quickie fun family gathering shooting, you can try this (I am not sure if it do-able on all brands of DSLR cam. ) if yours got live view, switch it on and if you adjust the whitebalance, the screen should react to the colour adjustment changes. adjust to your desire setting using the pre-set cloudy/sunny/tungsten/flouroscent setting or using the kelvin adjustment to finetune to the colour tone you find suitable for your shooting environment.
See if it works for u. Dun flame me if it doesnt ok. :angel: