Have you used the World Editor (warcraft 3 editor) before?
If you know how the editor works, you can open my map in the World Editor and change about everything you want.
Incase your new to the World / Warcraft 3 Editor, you can follow these steps to change the Protolisk:
1) open World Editor (World Editor.exe)
2) open my map in it (SH v1.7 (8) The Hunters.w3x , you will want to have the latest version, see this link
http://www.moddb.com/mods/starcraft-hybrids incase you still have version 1.4)
3) open the object editor (F6 is shortcut)
4) click on Units (upper left of the window), scroll down and look for 'Custom Units' on the left of the window. Below Custom Units you can find all the units used in this maps.
5) under 'Human' -> 'Melee' -> 'Units' and look for the name 'Protolisk', click it. Now in the right part of the window all the data for this unit is shown.
I am not going to much into detail here cause its just to much to explain here, but these links are very helpfull incase you want to learn it:
http://world-editor-tutorials.thehelper.net/uniteditor.php and
http://world-editor-tutorials.thehelper.net/models.php.
The first teaches what each button does in the unit editor. Second link explains how to import custom models so you can change the Protolisk model to for example the Marauder model.