This was discussed the other day. Yes, it is possible and I've done it that way. I didn't find it too bad a job. Just block the wishbone down out of the way and fish the old bolts up and out, then fish the new ones in and install the new crosspin to lock them in place. Then you can stick the felt up in a V fashion to fit on each side of the crosspin. If the bolt pockets are worn too much then the bolts will drop down far enough for the crosspin to not engage the head slots. If such is the case, then you will have to make spacers to fit under the bolt heads.
Before removing the old crosspin and bolts, lift the bolts up and down to check for excess wear in the bolt head pockets.