How can I make my vertex CUBE particle rotate while falling?

this is what I edited in EntityDiggingFX.class(yes, I'm doing this in MCP):

public void renderParticle(Tessellator p_70539_1_, float p_70539_2_, float p_70539_3_, float p_70539_4_, float p_70539_5_, float p_70539_6_, float p_70539_7_)
    {
        float var8 = ((float)this.particleTextureIndexX + this.particleTextureJitterX / 4.0F) / 16.0F;
        float var9 = var8 + 0.015609375F;
        float var10 = ((float)this.particleTextureIndexY + this.particleTextureJitterY / 4.0F) / 16.0F;
        float var11 = var10 + 0.015609375F;
        float var12 = 0.1F * this.particleScale;

        if (this.particleIcon != null)
        {
        	var8 = this.particleIcon.getInterpolatedU((double)(this.particleTextureJitterX / 4.0F * 16.0F));
            var9 = this.particleIcon.getInterpolatedU((double)((this.particleTextureJitterX + 1.0F) / 4.0F * 16.0F));
            var10 = this.particleIcon.getInterpolatedV((double)(this.particleTextureJitterY / 4.0F * 16.0F));
            var11 = this.particleIcon.getInterpolatedV((double)((this.particleTextureJitterY + 1.0F) / 4.0F * 16.0F));
        }

        float var13 = (float)(this.prevPosX + (this.posX - this.prevPosX) * (double)p_70539_2_ - interpPosX);
        float var14 = (float)(this.prevPosY + (this.posY - this.prevPosY) * (double)p_70539_2_ - interpPosY) - var12 / 2;
        float var15 = (float)(this.prevPosZ + (this.posZ - this.prevPosZ) * (double)p_70539_2_ - interpPosZ);
        p_70539_1_.setColorOpaque_F(1F, 1F, 1F);
        //TODO
        
        //var8, var9 - X U
        //var 10, var 11 - Y V
        
        //front
        
        p_70539_1_.addVertexWithUV(var13,         var14,         var15, (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13,         var14 + var12, var15, (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15, (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14,         var15, (double)var9, (double)var10);
      
        //back
        p_70539_1_.addVertexWithUV(var13 + var12, var14,         var15 + var12, (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15 + var12, (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13,         var14 + var12, var15 + var12, (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13,         var14,         var15 + var12, (double)var9, (double)var10);
        
        //left
        p_70539_1_.addVertexWithUV(var13, var14,         var15 + var12, (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13, var14 + var12, var15 + var12, (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13, var14 + var12, var15,         (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13, var14,         var15,         (double)var9, (double)var10);
        
        //right
        p_70539_1_.addVertexWithUV(var13 + var12, var14,         var15,         (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15,         (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15 + var12, (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14,         var15 + var12, (double)var9, (double)var10);
        
        //top
        p_70539_1_.addVertexWithUV(var13,         var14 + var12, var15,         (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13,         var14 + var12, var15 + var12, (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15 + var12, (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14 + var12, var15,         (double)var9, (double)var10);
        
        //bottom
        p_70539_1_.addVertexWithUV(var13,         var14, var15 + var12, (double)var8, (double)var10);
        p_70539_1_.addVertexWithUV(var13,         var14, var15,         (double)var8, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14, var15,         (double)var9, (double)var11);
        p_70539_1_.addVertexWithUV(var13 + var12, var14, var15 + var12, (double)var9, (double)var10);

    }

now how do I make the cube rotate randomly while falling? By adding some code to the onUpdate method in EntityFX perhabs?