All these POKEs [...] (from Chris Davis of Ludlow!) except the last can be used in both one-player and two-player versions. The first set removes all the sliding doors:

50375,0 50391,0 50616,0
50701,0 50758,0 50776,0
51015,0 51031,0 51074,0
51082,0 51167,0 51176,0
51186,0 51273,0 51323,0
51331,0 51470,0 51489,0
51494,0 51512,0 51629,0
51647,0 51656,0 51715,0
51753,0 51798,0 51819,0
51992,0 52233,0 52306,0
52310,0 52383,0 52456,0
52613,0 52713,0 53193,0
53343,0 53508,0

These POKEs destroy all the airlock doors:

50565,0 50569,0
50645,0 50649,0
50725,0 50729,0
52243,0 52250,0
52323,0 52330,0
52403,0 52410,0
52483,0 52490,0
52563,0 52570,0
53370,0 53372,0
52856,0 53016,0

And these POKEs destroy all the security doors:

50603,0 50608,0
50764,0 51008,0
51560,0 51721,0
52681,0

Now you should have no trouble getting into the place, at least. To enter the following POKEs, which are helpful for combat:

MERGE the header program, type STOP before the first RANDOMIZE USR statement, type RUN, load the game as normal, enter the POKEs, type CONTINUE.

To make the combat droids indestructible:

FOR i=61263 TO 61294:
POKE i,0: NEXT i

To make the men indestructible (and the androids indestructible when in fire mode):

FOR i=60846 TO 60878: POKE i,0: NEXT i

To destroy the three defence lasers:

POKE 53267,0
POKE 53646,0
POKE 53661,0

The next POKE only works on the two-player version. It changes the action points needed to fire to zero for the rebels and the operatives.

POKE 26705,120