This question was already answered by Radhakrishnan in an older post
How do I preserve hyperreferences in the index when converting text from LaTex to HTML, but I'm not able to get his solution to work.
The .idx and .ind files are successfully generated. However, executing the following command in the dos console tex '\def\filename{{test}{idx}{4dx}{ind}} \input idxmake.4ht'
gives me the error message
This is TeX, Version 3.1415926 (MiKTeX 2.9 64-bit)
! I can't find file `''.
\def
<*> '\def
\filename{{test}{idx}{4dx}{ind}} \input idxmake.4ht'
Please type another input file name:
Did I forget something? Any pointers to the cause of the problem would be appreciated.