Is there a reason you are using LanCraft? Lan should work fine out of the box. You may need to open the ports on your router that WC3 uses. (6112-6119.)
I'm confused, I thought your friend was the one with the PC.
Anyway, you could try Hamachi or this thing: http://noiz.yb.sg/testbed/
Quick google search brought that up, someone got it to work with WC3.
I don't understand though why emulating a lan would lessen your lag. I think you'd be better off improving your internet (use a wired connection?) and sticking to battle.net.
not sure if its relevant but recently any custom games you join that have a bot as the host you will get disconnected right at the start. blizzard has started disconnecting bots or something and as a result players get disconnected.
does what you are doing involve a bot of any sort? i've never heard of LanCraft. i've heard of hamatchi and it should be offline/LAN only so custom game bot shouldnt be affected but im not positive. this may be the case.