The university of surrey has a several zip files that contain IIF format data. This can be directly read as a zip file by the Cycom software. It will be converted to TBX format on saving from Cycom's software. http://www.computing.surrey.ac.uk/ai/new_interval/misc.html
Cycom's own sample TBX format creations include:
The TBX files can be checked and viewed with non-Cycom software such the TBX Checker tool from the TBX team. You will then need some extensible constraints and document type definition support files in XCSandDTDfiles.zip.
The SALT project can source files in DXLT format which are readable by Club Cycom TMS software.
[Cycom's TBX TMS software implementation]