gosh pen stain is gonna be tough. but if the cotton linning is not attached to the bag, maybe you can lift it up, dab alittle soap on it, just use a wet cloth and gently wipe it off. it is gonna take time. i have removed pen stains in my LV bag (suede linning) with WD40 oil and it worked. i am not sure about coach bags though.
I had an ink disaster with a leather coach bag too. I pulled the unattached lining out to work on it, and got most, but not all of it out using rubbing alcohol. In desperation, I used it on the leather too, and used an eraser designed to be used on suede, to rub off some of the ink stain. I knew I might damage the leather, but had nothing to lose. After much toil, it was vastly improved but still not fit for public display. I then took it to a shoe repair shop, and the guy sold me some tinted stuff to treat it with. I followed his instructions, and now it looks pretty much normal. Not perfect, but unnoticeable.
I had a disaster with ink in a coach that had no lining. So I started using plastic bags used for travel. Goody makes a set of 4 in different sizes.You can pick them up at the drugstore in the travel section. It protects your bag and you can find your stuff faster !
I have the metallic pewter Julia shoulder bag from Coach. I had a NIPS candy in my purse and it melted all over the inside (the lining-which is not metallic, it's a regular lining) of the purse and on my wallet. I used the Oxi Clean spray and a soft cotton cleaning cloth. I sprayed the Oxi Clean on the gooey stain and after a few minutes of spraying and rubbing, the entire gooey stain was removed!
I've used alcohol on a q-tip. Just pull the lining out and rub off the stains. It takes some time, but I got out quite a mess out of a beautiful pink patent Zoe! Make sure to let it dry well before inverting it back into the purse!