I have seen information about using AutoHotkey with Internet Explorer for form filling through COM interface.
Is there any possibility to do this using Firefox or Chrome?
The question is tagged AutoIt, so here's an AutoIt answer:
AutoIt does have a UDF for firefox automation that would do it. It's not a standard UDF and relies on a third party program.
Chrome has no interface for automation. In theory you could write a program that used webkit directly, and maybe even set the user agent to look like chrome. In practice I haven't seen it done, and it really is overkill when IE is a much easier choice for automation.