User blog comment:Aeinstein/Aein's Mod/@comment-26217614-20160910012730/@comment-25237422-20160910205127

all I did was changing the "mt.gif" file (added the new terrain and two halves of the castle), then, by the end of the javascript, there's a line of code starting with "qh.prototype.j=function" (in my modded version, it may be a little different in yours), in that line, there's a piece of code like "15658734==kb.f[a]?this.e[c][b]=6", the first number is the colour code of the new texture in the map files that are going to become the texture, and the last number is the position of the texture in the mt.gif file (it goes from 0 to 19)

You'll notice the mt.gif file is 80x64 pixels, the first 16x16 square is 0, the square in the right is 1, then 2, 3 and 4 (0 - 4 in the first line), then, 16 pixels down it's 5 - 9, then 10 - 14 and 15 - 19, so  "16777215==kb.f[a]?this.e[c][b]=19" would put the texture in the lower right corner of "mt.gif" where there's a #FFFFFF colour in the map files