I recommend the wheelpress and quartering jig from GW Models, cost £25-£30. Phone 01903 767231 to confirm price and postage. George the proprietor is elderly so there is no website. Expect to pay by cheque. His address was 11 Croshaw Close, Lancing, West Sussex BN15 9LE. I hope he has not moved!
The GW press will only work with finescale wheels (Alan Gibson and Ultrascale). If you re-use RTR wheels (e.g. the Dapol B4 wheel is not available in finescale), then I use the Bill Bedford quartering jig; cost £7.90 from Wizard Models: