once fixing a friends mk2 and he cranked it while I was holding the the central lead, got thrown across garage! he thought it was fun I didn't.

be careful when doing this! put a sparkplug in the connector at end like normal and hold it against the block. wear marigolds too if you are not sure you will feel it but it does help a lot if wearing rubber gloves and make a mistake!

disconnecting injectors is a good idea as you don't need atomised petrol around sparks!