carefully unclip the brake lines along the firewall , one at a time, use something to keep the modulator propped up , if you have a 4 or 5mm allen bit (it's one of those sizes:-)
the other end of the allen bit is usually 10mm , so that end fits in a 10mm ratchet spanner , if you don't have those tools you could cut down an allen key and use it with 1/4 drive ratchet

