I really can't help you with this. I recommend you use VNC
for Unix/Linux/Mac or Remote Desktop if using Windows.
If you must use logmein.com, then try this:
- Disable FoxyProxy's Connection Settings for the proxy you want to use. This will update Firefox's preference settings--the settings that logmein.com probably reads
- Enable FoxyProxy
Now FoxyProxy will work as usual, but hopefully logmein.com will read Firefox's settings as usual, too. FoxyProxy does not use Firefox's proxy settings so there is no conflict.