Sorry man, this will not work at all. Bubblebags go by the principal that the smallest part of a bud is the trichome. When you would normally do this, bud or trimmings are brought to freezing and agitated, allowing the trichomes to break free from the plant material and be filtered through progressively fine screens. This presumably allows the finest part to be caught by the last filter, which is the best hash.
With ashes, the plant material has been broken down to much smaller pieces allowing it to pass through the screens. More importantly, any exterior trichomes or trichomes which may have become available during the normal agitation process have been melted and burned into the plant matter. This will make them inseparable from the ash, and you will most likely end up with some sort of dirty ash-resin hash.
Your best bet to get something worth smoking out of roaches or old ash is a butane or alcohol extraction. In these methods of making hash the THC is actually dissolved in a liquid which allows it to pass through a filter in liquid form. This might get the ash caught up in whatever filter you use, but I've never personally tried it. If you do give this a try let me know how it turns out.