You probably won't find many on here old enough to have tried it. It's not used anywhere anymore. You'll sooner find some pharm diamorphine or methaqualone then a Doriden.
The cool thing about glutethimide is that in addition to being a strong downer in it's own right, it induces CYP2D6 like you said, and blocks the primary way opiates are metabolized by glucuronidation at the 3-hydroxy to the inactive morphine-3-glucuronide. This means that in addition to making codeine stronger, it makes it last much longer too. It might work for other opiates too, even non-prodrugs like morphine or hydromorphone.
I'd really like to try the doors and fours combo, maybe with some lean to make some pancakes and sizzurp:D. Even better use Vicodin, oxy or even Ultram instead. I think I read that the original 'load' was like 4 tylenol#4(240mg codeine phosphate) and 2 Doridens(1000mg). Although I've never tried it nor has anyone I know, it sounds kind of risky.
The downside is I think it's about as toxic as amobarbital when adjusted for potency differences, and it metabolizes into something twice as strong. Although I don't think it has barbs' fuck up tolerance pattern, where the tolerance to the euphoria rises faster than to the toxicity, the lethal dose(2 grams) never rises above twice the non-tolerant lethal dose, and the tolerance to the euphoric effects levels off at 1.5 grams, leaving a razor thin line between feeling good and death. Could be wrong about that with Doriden.
Kind of wish it was around still, but in this age of oxy hysteria and seeing how stupid people can get with pills, probably for the better, as much as it pains me to say it. I mean I hate that it's one of the DEA's rare victories but I could see the bodies stacking up if it potentiates oxycodone like codeine.