I'll try...
1.) The menus in ST (all the icons on top and the toolbars they open) are no longer hardcoded, but can be configured via a file called menuconf.tab (located in pak\config\)
2.) waytype=maglev_track is not a double for monorail_track - it's going to be a completely different (new) waytype.
3.) The standard toolbars, as provided by the paksets, do not (yet) include the tools&icons for maglev_track - just rail, monorail, tram, road, ship and air.
So you'd need to edit your menuconf.tab in a way that makes the maglev_track icons and toolbars visible in game.
You can do that in 2 ways:
1) The long and elegant (and probably "correct") way is to insert a new toolbar for the maglev-waytype tools somewhere between the others. That requires quite a bit of shuffling, since all these entries are numbered and have to be kept in correct order (=so that the index numbers always increase). That means, you can't just insert the new item somewhere in the middle - you can insert it and then increase the index number of all following toolbars. Example:
A(1)
B(2)
C(3)
D(4)
E(5)
if you want to enter Z between B and C, you can do so - but you hav to work over C, D and F then.
A(1)
B(2)
Z(3)
C(4)
D(5)
E(6)
This can be quite tedious, and errors are easily made.
2.) The other way is the quick and dirty method - not really correct and not well suited for long-term-use, but surely good enough for testing:
Search for the section that looks like this
# monorailtools (waytype 5)
toolbar[3][0]=ways(5,0)
toolbar[3][1]=ways(5,1)
toolbar[3][2]=bridges(5)
toolbar[3][3]=tunnels(5)
toolbar[3][4]=wayobjs(5)
toolbar[3][5]=signs(5)
toolbar[3][6]=general_tool[17],18,,5
toolbar[3][7]=buildings(33,5)
toolbar[3][8]=buildings(34,5)
toolbar[3][9]=buildings(35,5)
and add the following lines:
toolbar[3][10]=-
toolbar[3][11]=ways(6,0)
toolbar[3][12]=ways(6,1)
toolbar[3][13]=bridges(6)
toolbar[3][14]=tunnels(6)
toolbar[3][15]=wayobjs(6)
toolbar[3][16]=signs(6)
toolbar[3][17]=general_tool[17],18,,6
toolbar[3][18]=buildings(33,6)
toolbar[3][19]=buildings(34,6)
toolbar[3][20]=buildings(35,6)
The first line gives you a blank icon as border and then all tools from monorail (waytype 5) are replicated just with waytype 6 (=maglev).
That way, when you open your monorails tools in ST, the toolbar will show you all monorail tools, then a balnk icon, and then all maglev tools.