Example of the stuff you have to read through to do the changes you want:
.text:200B9553 mov edx, [esp+2980h+var_2970]
.text:200B9557 push 64h
.text:200B9559 push 7
.text:200B955B push edx
.text:200B955C push ebp
.text:200B955D push edi
.text:200B955E call sub_20032790
.text:200B9563 mov eax, [edi+110h]
.text:200B9569 mov ebp, 1
.text:200B956E mov [eax+1190h], bp
.text:200B9575 mov ecx, [edi+110h]
.text:200B957B mov [ecx+118Ch], bp
.text:200B9582 mov edx, [edi+110h]
.text:200B9588 xor ebx, ebx
.text:200B958A mov [edx+1194h], bx
.text:200B9591 mov eax, [edi+110h]
.text:200B9597 mov cl, [eax+274h]
.text:200B959D add esp, 14h
.text:200B95A0 test cl, 4
.text:200B95A3 jz short loc_200B95C7
.text:200B95A5 fild [esp+2980h+var_296C]
.text:200B95A9 mov ecx, dword_201F4B54
.text:200B95AF sub esp, 8
.text:200B95B2 fmul dword ptr [ecx+1Ch]
.text:200B95B5 fstp [esp+2988h+var_2988]
.text:200B95B8 call _floor
.text:200B95BD add esp, 8
.text:200B95C0 call __ftol2
.text:200B95C5 mov esi, eax
You can get it a bit clearer than that if you have the right tools, but in the end you'll have to find exactly where in this where you gotta change stuff.