good.
sussed that out ...
now...
"custom os on your desktop pc" doesn't illumine exactly what you are running.
sooo...
what are you running?
what you are running will tell me what kind of help I'll be or whether you will need someone who is savvy in your particular os.
win of some kind?
mac of some flavour?
linux?
bsd?
gentoo?
another source based linux?
something odd or unlikely or rare?
I've messed with and run a few obscure os's...


If you want to fart around in your particular os and try to get devices/os's to recog. each other .. go for it.
I can't help there..

otherwise
easiest, simplest, most prob free suggestion is..
don't muck up your custom whatever...
install vmware...
install win xp or 7 [can be libusb persnickety ...] ...
or install buntu ..or debian on the vmware and you shouldn't have any probs from there...there are explanatory guides better'n me... out there for that ...

As far as help goes...
the walkthrough in my sig ["pimp my n8x0"] ...
is as easy as it will ever ever ever everevervreevr get.
You will not find an easier to understand guide...
nor a more comprehensive guide for the n8x0
and there is the video walkthrough as well.
Just follow exactly what is done.
There is nothing confusing or hard about the walkthrough..
just pick what outcome you wish and use the described methods to achieve it.
The walkthrough and vids initially deal with the simplistic gui of nokia's software wizard which works for xp and win7 to flash the firmware...[I used xp and win7 for the walkthroughs since most who come to maemo are coming from M$...]
after flashing... it is universally the same process from that point on concerning tweaking your n8x0 ... regardless the os....so your custom pc os has little bearing after that.