I use this as one of the custom commands:
S8000 M3;
G04 P50.;
S10000 M3;
G04 P50.;
S12000 M3;
G04 P50.;
S14000 M3;
G04 P50.;
S16000 M3;
G04 P50.;
S18000 M3;
G04 P50.;
S20000 M3;
G04 P50.;
S22000 M3;
G04 P50.;
S24000 M3;
G04 P50.;
M30;