Cutting was quite easy to make, I really just used one file to do so.
I did cut that plastic around the Ultra-bay videocard, drilled nicely some holes (so it looks like original, huh) in lower cover of laptop (where the fan of Ultra-Bay is situated), cut out some plastic around copper pipes from CPU.
After that temperatures for the Ultra-Bay were quite good, not reaching more than 89-92 degrees (before 95-97 stable in heavy games).
But it was not enough for me, and I did repasting and Spacer mod for both Motherboard and Ultrabay. Funny thing...now Ultra-Bay have lower temperature mostly, than main Videocard, and CPU now looks like heating also more.. interesting for me, if the reason is bad quality of thermalpaste or Spacer mod. But still, it does not reaching more than 90 deg C, so it's OK.
Keep monitoring now, later hope to make Bios Mod and try undervolting also.