You don't want to have any grease in or near the bush, when the new one goes in, as it will always migrate onto the friction plate by centrifugal forces...
The best way to ensure lubrication of the bush is to get a tin can or similar and fill with engine oil till it just covers the bush...
Then heat the tin over the stove for little while and then let the bush sit soaking in the oil till cool or best overnight...
This will sinter the bush with the oil, then take the bush out of the oil, wipe off excess oil and let it sit for an hour or so to let any extra surface oil bleed out...
Then you can insert the bush in the flywheel... The oil should assist insertion and will be more than sufficient to lubricate the pinion...