The EWS3 immobiliser looks like this........
....and is bolted to the drivers side A pillar directly behind the light switch module.
It is secured with two bolts, with normally a TS30
five point security Torx Plus head, however some very early models have plain 8mm hex head M5 set screws.
A cheap set like
THIS would suffice to remove the unit in most cases
Not a particularly difficult item to remove, I've done hundreds and as to size, it's physically about the size of a packet of 20 cigarettes, and can be placed in a jiffy bag to post
Brian