To enter the swirly tilda "~"
Press the top 2 keys on the left (blue arow and Sym keys)
Select ~ in resulting symbol list
Press Space key (no idea why, just tried "likely" keys until it worked)

javispedro's shortut to getting a virtual SD card works on the N900

Run X Terminal
As reposted previously, enter following:

$ mkdir ~/.gvm/cards
$ echo -e "/media/mmc1\nRW" > ~/.gvm/cards/0

I haven't tried installing via it yet, but hope this helps.