Can OE6 be installed on a flash drive?

(Long story re dialup vs high speed in my area) but I have to use dialup, no
alternative at present. Large emails choke my line, so I sequester them on
the web-based server.
AT&T used to have a great in-house webmail system, but due to degenerative
cognitive disease, they switched to Yahoo Mail base.

So now, when I have the large files, I still have to get to a high-speed
computer (usually at the library) to read them. Earlier, with the old AT&T,
I could archive any number of selected msgs and have them d/loaded to my
flash drive in a zip format. However, now, Yahoo doesn't allow that group
zipping.

To solve this, I want to install a client email program onto a flash drive,
use it to d/load the large msgs; then I want to transfer those messages at
home onto my OE6. (Don't ask why I need to do this, it's just easier for me
to work it this way in the long run...) I could do it all with the old AT&T
system...

I'm trying Thunderbird Portable, which d/loads the msgs fine; but it won't
let me transfer them over to an OE folder or even a Windows folder.

Incidently, when using a public computer, I cannot invoke the T-bird from
the flash drive; local restrictions apply. So I have to get to somebody
else's high speed computer, where it works fine at d/loading...

Ideas? Suggetions?