The important thing to do the mod without soldering is holes in the plate - pop off a keycap, if the holes are tight around the switch you'll need to desolder, if there's a long thin gap or two short gaps down the sides you can take the tops off and do the mod.
If you can do it you'll need a tool to take the switch tops off, you can make one or if you're in the US you can buy
these, if you're non-US send a
PM to 00zeRo (who runs the site) and he can send a paypal invoice without the expensive insured shipping.
As to the springs it's personal choice, if you use heavy keycaps you may find they don't pop up reliably using brown springs but they're free so could be a good place to start.