1. Pick a tree name such as mytesttree.
2. Define the tree path environment variable and create the target directory.
3. Create a model tree in mdstcl.
4. Add nodes with Traverser or TCL.
5. Create a pulse number and write test data from IDL.

export mytesttree_path=/u/yourname/testtreedir
mkdir testtreedir
mdstcl

TCL> edit/new mytesttree
TCL> set tree mytesttree
TCL> create pulse 10
TCL> exit

IDL> MDSOPEN, 'mytesttree', 10
IDL> x = FINDGEN(10) & data = x^2
IDL> MDSPUT, ':onedim', 'build_signal($,*,$)', data, x