Upgrade to 11.10 - not enough space on root.

[ReguPL]

Hello!
I tried to upgrade form 11.04, update manager downloaded packages and then while unpacking it showed "not enough room on root" and asked to make another 700MB free.

I already browsed through forums and cleaned what I could: old apts, logs etc. and deleted some apps. My disk is small, so partition resize is not an option. I also downloaded 11.10 .iso My questions are:

1. Is it possible to redirect downloading upgrade to another partition (pendrive)?

2. Is it possible to upgrade from mounted .iso?

... and if yes, of course how? :)

thanks in advance,
Andrzej