What did you try doing. You just need to do:
BLAH BLAH <RGB(100,100,100)> BLAH BLAH <RGB(200,200,200)> BLAH BLAH
Basically, the first BLAH BLAH will be normal text colour. The second BLAH BLAH will be in RGB(100,100,100) and the third BLAH BLAH will be in RGB(200,200,200).
You must leave a space at either end of <RBG(100,100,100)>
BLAH BLAH <RGB(100,100,100)> BLAH BLAH <RGB(200,200,200)> BLAH BLAH
Basically, the first BLAH BLAH will be normal text colour. The second BLAH BLAH will be in RGB(100,100,100) and the third BLAH BLAH will be in RGB(200,200,200).
You must leave a space at either end of <RBG(100,100,100)>