Oh yea, that can be a pain. Pretty hard to describe...how many clips? too many

You need a molding tool. Took me a bit of practice to learn how to use it. THe tool does not slide under the windshield gasket rubber. It slides between the rubber and the chrome. What you are trying to do, is get that sharp point under clip andslightly pry it inbard towards the center of the windshield-away from the lip on the chrome molding. THis only makes it possible to pul the chrome up. Does not actually lift the chrome-just pulls the clip away. ANd slightly means SLIGHTLY. It will be really stiff anyway. ANd will take a good deal of force. I use plastic chisils to pry the chrome up in one corner and start releasing clips. One at a time. If you have original chrome trim in good shape-take your time and don't damage it. I've never used the repop stuff, but have heard t's pretty poor fitting.
THis a really hard to describe. It would be advisable to have some one assist that has done this before so you can see ow it comes off.
SOrry, didn't read the whole post. If yo have the Y tool, like I said, the point goes under the clip. ANd "under" is misleading, it really catches an edge of the clip. THe side if the Y not under the chrome (the other end) gets braced against the rubber gasket. Keep moderate pressure sideways to keep the tp uder the edge of the clips, and pull the handle so the force is pulling the clip away from the chrome as described above. Start lifting the chrome.
Note: Original never removed chrome can sometimes have LOTS of hard, clay like goop (factory sealer) that will make finding the clips with the tool nearly impossible. You can only feel them. Again, take your time, use the tool to carefully scrape the goop out of the way till you can dig down to the clips.
Last note: frustration with this task can lead to excessive force on the tool resulting in skating the tool accross your hood at high speed...ask me how I know...