Generally speaking valve would probably have a legitimate claim.
But out of the books in real live this aint a problem.
As long as it's in valves best interest to let me be, they will.
I'm only adding to the HL2 rage.
At valve they are also doing their best to keep the rage fresh.
They have made ascii pictures in source.
And g-mans appearing on their main site.
And test and stuff.
So i think what i'm doing is completely legal as long as valve doesnt mind.
Life is too short to be afraid.