I don't know anything about spring pullers but an old mechanic taught me how to stretch the springs on the centerstand for my guzzi.
Get a friend, couple of vice grips and a pocket full of pennies or washers. Clamp on to the ends of the spring and flex it over. One side of the spring will expand enough to allow your buddy to jam some pennies in the gaps. Let go and turn it over and do the other side. Soon enough, you'll have a fairly expanded spring (and muscles like popeye from flexing the spring) that you can just fit over both the post on the bike and the post on the centerstand. Then all you have to do is put the center stand up and down a few times and the coins will fall out by themselves. If not, you've got your handy vice grips right there. Any coinage will work, but it won't be accepted by vending machines at your finer establishments afterward.
I'm sure you experienced shop guys already knew this or have some dedicated tool in your well stocked garage. For me, it was one of those AHHHhhhha moments.
Of course, the BMW probably has some sort of pneumaticly activated spring mechanism that makes all this irrelevant.