[Nero_3D]

With bitwise operation you would basically do the same
Also nearly all colors in sa-mp are stored in RGBA

color = 0xFFFF00FF; // Yellow with full alpha

First you would extract each color

red = color >>> 24; // shifting everything by 24 bits to the right
green = color >> 16 & 0xFF; // shifting and extracting the rightmost 8 bit
blue = color >> 8 & 0xFF;

After that you simply multiply it and check if it went over 255
Additionally be sure that VALUE is a positive number

red = min(0xFF, red * VALUE); // same for green and blue

At the end you put it together

color = red << 24 | green << 16 | blue << 8 | color & 0xFF;