This requires loadmodule plugin be enabled. It is by default.
In Joomla 1.5 Administrator:
Plugin Manager >> Content - Load Module
Put this tag in Article content at the point where the module should appear, including curly brackets:
{[loadposition positionName]} (remove square brackets [], keep curly brackets {} )
postionName to be replaced with the name of a template position.
Use a template position not being used in your template.
Assign module to this position using Module Manager.
If a new postion is required, add it to the templateDetails.xml file at templates/yourtemplate/templateDetails.xml.
The positions are listed in templateDetails.xml between the <positions> and </positions> tags.
The new position will then become available for selection in the Module Manager.