Fitting new fuel pump TD5, any tips?

New fuel pump arrived today but despite the heavy rain I have had to attempt to fit it as I've no transport. Its easy enough to fit and connect up the pipework etc, but bloody difficult to hold down the pump on its spring mounting and re-fit the collar. Its takes all my strength to push the thing down but impossible to hold the pump down and fit and turn the securing collar all at the same time (not helped by everything being wet and blowing a gale). Has anyone found a way of holding the pump down sufficiently tight to fit the collar? All suggestions welcome (well, almost all )

Done mine last month as it gave up half way home from Edinburgh so road side repair it was.

Found it was easier to fit the rubber seal to to the tank first and get it in right then it helps hold the pump in place a small amount.

Even after that still had to lean on the pump to keep it down and had a fight with the coller to get it not to cross thread.

Thanks minidod, will try fitting the rubber seal first, hopefully that should do it. I like the way the haynes manual tells you how to do it 'Refitting is a reversal of removal..