Thank you for the help. I was able to run configure.py (also needed to install Visual Studio 2015 because it doesn't work with 2013, but didn't say that until I was on the last step) and was able to configure it and using VS2015 Native Tools command prompt run ambuild. However, the build has failed and it seems like there are a bunch of errors in SM's core.
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(32
: error C2369: 'PTR': redefinition; different subscripts
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(321): note: see declaration of 'PTR'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(339): error C2296: '*': illegal, left operand has type 'float *'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1089): error C4235: nonstandard extension used: '__asm' keyword not supported on this architecture
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1092): error C2065: 'fld': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1092): error C2146: syntax error: missing ';' before identifier 'f'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1092): error C2146: syntax error: missing ';' before identifier 'fistp'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1093): error C2065: 'fistp': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1093): error C2146: syntax error: missing ';' before identifier 'nResult'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1093): error C2143: syntax error: missing ';' before '}'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1126): error C4235: nonstandard extension used: '__asm' keyword not supported on this architecture
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1129): error C2065: 'fld': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1129): error C2146: syntax error: missing ';' before identifier 'f'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1129): error C2146: syntax error: missing ';' before identifier 'fistp'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1130): error C2065: 'fistp': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1130): error C2146: syntax error: missing ';' before identifier 'nResult'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1130): error C2143: syntax error: missing ';' before '}'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(1165): error C4235: nonstandard extension used: '__asm' keyword not supported on this architecture
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: error C2065: 'fld': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: error C2146: syntax error: missing ';' before identifier 'f'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: error C2146: syntax error: missing ';' before identifier 'fistp'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: error C2065: 'fistp': undeclared identifier
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: error C2146: syntax error: missing ';' before identifier 'qword'
c:\users\administrator\desktop\alliedmodders\ hl2sdk-tf2\public\mathlib/mathlib.h(116
: fatal error C1003: error count exceeds 100; stopping compilation
Build failed.
This is just a sample, it goes on for a LONG time. And I'm not sure what exactly I've done wrong, or how to fix this. The Building SourceMod page makes no mention of these problems, or how to resolve them. This is also not problems with my own code, but the errors are from SM core (I'm also building an already existing extension)... leading me to believe the problem is the build setup. If anyone knows how to fix these build errors, that would be appreciated.