How to make tree menu from flat XML

Hi, I have this XML, and I want to make tree menu. The
roots elements of tree menu are the records with
keynum < -100, the children of the root elements are
records with keynum between -50 and 0 and
parentkeynum=keynum of the root, and the third level
of the tree menu are records with keynum > 0, and the
parentnumber shows the keynum of their parent. Please
help me.
XML file:


<?xml version="1.0" ?> 
- <records>
- <record>
  <keynum>-1</keynum> 
  <keyname>2 CLIENTS HAVE A NEGATIVE BALANCE</keyname>

  <parentkeynum>-100000</parentkeynum> 
  <rowcnt>2</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>35</keynum> 
  <keyname>35 MR. MICHAEL NOLAN</keyname> 
  <parentkeynum>-1</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>-275</balance> 
  </record>
- <record>
  <keynum>142</keynum> 
  <keyname>142 MR. JOHN CALINSKI</keyname> 
  <parentkeynum>-1</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>-11</balance> 
  </record>
- <record>
  <keynum>-3</keynum> 
  <keyname>42 CLIENTS CREDIT IS GREATER THAN
BALANCE</keyname> 
  <parentkeynum>-100000</parentkeynum> 
  <rowcnt>42</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>18</keynum> 
  <keyname>18 MRS. LYNN BONIN</keyname> 
  <parentkeynum>-3</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>35</keynum> 
  <keyname>35 MR. MICHAEL NOLAN</keyname> 
  <parentkeynum>-3</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>-275</balance> 
  </record>
- <record>
  <keynum>43</keynum> 
  <keyname>43 MR. JAMES D. NEFF</keyname> 
  <parentkeynum>-3</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>0</balance> 
  </record>
.................
.................
.................
- <record>
  <keynum>10006</keynum> 
  <keyname>10006 MR. DALE SPONSEL 2003-04-24</keyname>

  <parentkeynum>-16</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>-100003</keynum> 
  <keyname>APPOINTMENT ALERTS (1)</keyname> 
  <parentkeynum>0</parentkeynum> 
  <rowcnt>1</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>-100002</keynum> 
  <keyname>HAIR SYSTEM ALERTS (2)</keyname> 
  <parentkeynum>0</parentkeynum> 
  <rowcnt>2</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>-100001</keynum> 
  <keyname>PROGRAM ALERTS (2)</keyname> 
  <parentkeynum>0</parentkeynum> 
  <rowcnt>2</rowcnt> 
  <balance>0</balance> 
  </record>
- <record>
  <keynum>-100000</keynum> 
  <keyname>FINANCIAL ALERTS (5)</keyname> 
  <parentkeynum>0</parentkeynum> 
  <rowcnt>5</rowcnt> 
  <balance>0</balance> 
  </record>
  </records>

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