You have two possibilities.
Either try to use especially for this purpose the older
K-Meleon version 0.9.13 , downloading its zip-version
and unzip it into a fresh, additional folder, and enable
the ActiveX function in Tools/Privacy/Permissions.
You can have different unzipped K-Meleon versions
on your computer, but only use one or the other at
the same time. Nevertheless it is not sure, if the
online virus scanner works with the Active X plugin
in the default, comparatively safe setting.
All online scanners demand basically Internet Explorer.
I would rather propose to install a free virus scanner
as for example AntiVir, which is small, effective
and offers frequent online updates.
Download at :
http://www.free-av.com/
The online scanners may also demand the download
of Active X Controls of considerable size.
Fred