if you don't want to use a side wheel then try a fishing coaster various ones are available these give a 'handle' which makes it very easy to focus without having a wheel to contend with. All fishing tackle shops should sell them for between £6-£12 for a pair. For record had one of these exact swats from JSR and never had any probs in any light and worth every penny for the quality you get.
Theoben TTR2 .20 KevG reg, PhilD valve and Ti stem, Bucketboy mod'd barrel and custom silencer / Weihrauch HW100KT .22