the short tool will work if you cannot remake mysqldump without extended-insert option.

mysqldump_split_insert.py

# -*- coding: utf8 -*-

import sys

BOL, LCOMMENT, INSTMT, INSERT, VALUES, QUOTE_VALUE = range(6)

CHUNK_SIZE = 1024 * 1024 * 1 / 2 # 512k in read
stock = ''

def next():
    return sys.stdin.read(CHUNK_SIZE)

def write(buf):
    sys.stdout.write(buf)

state_stack = [BOL]
insert_stmt = ''
stock = next()
rp = 0
np = 0
while True:
    rp = np
    if len(stock) - rp < CHUNK_SIZE or stock[-1] == "\\":
        write(stock[:rp])
        stock = stock[rp:] + next()
        rp = 0
        if not len(stock):
            break
    p = state_stack[-1]
    if p == BOL:
        if stock.startswith('INSERT INTO', rp):
            state_stack.append(INSERT)
            np = stock.find('(', rp)
            write(stock[:rp])
            insert_stmt = stock[rp:np]
            stock = stock[np:]
            np = 0
        elif stock[rp] == "\n":
            np = rp + 1
        elif stock.startswith("--", rp):
            state_stack.append(LCOMMENT)
        else:
            state_stack.append(INSTMT)
        continue
    if p == LCOMMENT:
        i = stock.find("\n", rp)
        if i >= 0:
            np = i + 1
            state_stack.pop()
            continue
        np = len(stock)
        continue
    if p == INSTMT:
        i = stock.find(';', rp)
        if i >= 0:
            qp = stock.find("\\'", rp, i)
            if qp >= 0:
                i = qp
                state_stack.append(QUOTE_VALUE)
            else:
                state_stack.pop()
            np = i + 1
            continue
        i = len(stock)
        qp = stock.find("\\'", rp, i)
        if qp >= 0:
            i = qp + 1
            state_stack.append(QUOTE_VALUE)
        np = i
        continue
    if p == INSERT or p == VALUES:
        if p == VALUES:
            state_stack.pop()
        if p == INSERT:
            write(insert_stmt)
        i = stock.find(')', rp)
        if i >= 0:
            np = i + 1
            q = stock.find("'", rp, np)
            if q >= 0:
                np = q + 1
                state_stack.append(VALUES)
                state_stack.append(QUOTE_VALUE)
                continue
            write(stock[:np])
            if stock[np] == ',':
                write(";\n")
            elif stock[np] == ';':
                state_stack.pop()
                write(';')
            np += 1
            stock = stock[np:]
            np = 0
            continue
        state_stack.append(VALUES)
        q = stock.find("'", rp)
        if q >= 0:
            np = q + 1
            state_stack.append(QUOTE_VALUE)
            continue
        np = len(stock)
        continue
    if p == QUOTE_VALUE:
        i = stock.find("'", rp)
        if i >= 0:
            bs = stock.find("\\", rp, i)
            if bs >= 0:
                np = bs + 2
                continue
            np = i + 1
            state_stack.pop()
            continue
        np = len(stock)
        continue