I did this with a couple of my Mcdavid YGs from epack. The process is to transfer the card from epack to COMC. Then on COMC (in the inventory manager) you can select to have your card graded by BGS. They offer a few different service levels, so you can choose the speed of service. The card then gets returned back to COMC and back into your inventory.
Its convenient if you dont want to deal with packaging and shipping to BGS yourself, or dont have a LCS that sends cards in. The downfall is the price is a lot more than if you sent in yourself and also that the image on COMC is just so-so, so to a certain degree, you are taking a risk on how clean the card is. In general though, the majority of cards from epack (especially YGs and YGC) seem to be fairly clean and tend to grade fairly well.
