No I've not drilled mine but I really should.
I didn't because (a) I'm scared and (b) it would invalidate the warranty.
The warranty isn't an issue for you because it's second hand, and although it's a lifetime warranty I bought mine in the US over 5 years ago and have no idea where the receipt is so it probably isn't realistic for me either.
Pretty sure that both @skinny and @danstuff have done some drilling on Cervelo frames though.
What I really want is an e-tap RD so I don't have to worry about cabling at all, but tap isn't available as separate components to my knowledge, and I'd probably have to wait for a second hand one anyway.