Usability testing is technique for analysis of the usability problems of applications, but it requires significant effort to prepare the test and especially to analyze data collected during the test. New techniques such as usage of task models were introduced to improve and speed up the test analysis. Unfortunately, only few applications provide the task model. Therefore, we propose a method and tools for partial reconstruction of the task list and the task model called skeleton. This reconstruction is done from the usability expert's application walkthroughs. The task model skeleton is generated automatically, but it should provide similar information during the usability data analysis as manually created full-scaled task model. In order to evaluate usage of the task model skeleton we conducted a usability study with the web e-mail client Roundcube. Results show that the task model skeleton can be used as a good substitution for the manually created task model in usability testing when full-scaled task model is not available.