unfortunately this script is very old, and i do not go to irc anymore.
but, if you would like to edit them yourself, just use the inbuilt "find" feature of mirc's script editor and search for
;-------------------------------------------------------Themes

under that line is where the themes are stored.
eg:

  ;--Row 1
  if $did = 302 { set %themenumber 1 | set %theme1 4,1>14,1>15,1>0,1>4 | set %theme2 0,1<15,1<14,1<4,1< | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 303 { set %themenumber 2 | set %theme1 4,1<14,1<15,1<0,1<14 | set %theme2 0,1>15,1>14,1>4,1> | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 304 { set %themenumber 3 | set %theme1 4,1>7,1>8,1>0,1>4 | set %theme2 0,1<8,1<7,1<4,1< | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 305 { set %themenumber 4 | set %theme1 4,1<7,1<8,1<0,1<14 | set %theme2 0,1>8,1>7,1>4,1> | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 306 { set %themenumber 5 | set %theme1 6,1>6,1>13,1>13,1>13 | set %theme2 13,1<13,1<6,1<6,1< | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 307 { set %themenumber 6 | set %theme1 6,1<6,1<13,1<13,1<13 | set %theme2 13,1>13,1>6,1>6,1> | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  ;--Row 2
  if $did = 308 { 
    set %themenumber 7
    set %ass1 (_|_)
    set %ass2 (_/_) (_|_) (_\_)
    if (%music.gender == $null) { set %music.gender $input(His OR Her?,Settings,n,what is your gender?) }
    if (%music.gender == his) { set %theme1 $rainbowtext(Shakes his) 12,1 $+ %ass1 $+ 11,1 | set %theme2 12,1 $+ %ass2 | did -ra music.player 315 $strip(%theme1 %theme2) | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
    if (%music.gender == her) { set %theme1 $rainbowtext(Shakes her) 13,1 $+ %ass1 $+ 6,1 | set %theme2 13,1 $+ %ass2 | did -ra music.player 315 $strip(%theme1 %theme2) | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  }
  if $did = 309 { 
    set %themenumber 8
    set %hand1 4,1|..|, 14,1
    set %hand2 4,1,|..|
    set %theme1 4,1H14,1ea4,1DB14,1ang4,1Z %hand1 | set %theme2 12,1 $+ %hand2 | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 14,1SongName %theme2 %theme1 14,1SongLength %theme2 
  }
  if $did = 310 { set %themenumber 9 | set %theme1 4,1[14,1 | set %theme2 4,1] | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 311 { set %themenumber 10 | set %theme1 4>6,1>13,1>0,1>13,1 | set %theme2 0,1<13,1<6,1<4,1< | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 312 { set %themenumber 11 | set %theme1 4,1[12,1 | set %theme2 4,1] | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 SongName %theme2 %theme1 SongLength %theme2 }
  if $did = 313 { set %themenumber None | unset %theme1 | unset %theme2 | did -ra music.player 315 No Theme | //echo -a SongName SongLength }
  if $did = 317 { set %themenumber 12 | set %theme1 4_(\7\/8/ | set %theme2 8\7\/4/)_ | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 14,1SongName %theme2 %theme1 14,1SongLength %theme2 }
  if $did = 318 { set %themenumber 13 | set %theme1 4,1xX14,1‡4,1Xx14,1 | set %theme2 4,1xX14,1‡4,1Xx | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 14,1SongName %theme2 %theme1 14,1SongLength %theme2 }
  if $did = 319 { set %themenumber 14 | set %theme1 5-4-5-14 | set %theme2 5-4-5- | did -ra music.player 315 %theme1 %theme2 | //echo -a %theme1 14,1SongName %theme2 %theme1 14,1SongLength %theme2 }
  if $did = 320 { set %themenumber 15 | set %theme1 $rainbowtext(¯`·.¸¸¸.·´¯`·.¸¸¸.->) | set %theme2 $rainbowtext(<-.¸¸¸.·´¯`·.¸¸¸.·´¯) | did -ra music.player 315 $strip(%theme1 %theme2) | //echo -a %theme1 14,1SongName %theme2 %theme1 14,1SongLength %theme2 }
  if $did = 321 { set %themenumber 16 | set %theme1 4(¯`·.¸¸¸.·´¯`·.¸¸¸.->14 | set %theme2 4<-.¸¸¸.·´¯`·.¸¸¸.·´¯) | did -ra music.player 315 $strip(%theme1 %theme2) | //echo -a %theme1 14SongName %theme2 %theme1 14SongLength %theme2 }

  if $did = 210 { write -ds $did(music.player,203).seltext CustomChanPlayList.txt | did -r music.player 203
    %a = 1
    %b = $lines(CustomChanPlayList.txt)
    while %a <= %b { did -a music.player 203 $read(CustomChanPlayList.txt, %a) | inc %a }
  }
  if $did = 211 { did -a music.player 203 $did(music.player,201).seltext | write CustomChanPlayList.txt $did(music.player,201).seltext }
}

one for example is:
if $did = 320 { set %themenumber 15 | set %theme1 $rainbowtext(¯·.¸¸¸.·´¯·.¸¸¸.->) | set %theme2 $rainbowtext(<-.¸¸¸.·´¯`·.¸¸¸.·´¯) | did -ra music.player 315 $strip(%theme1 %theme2) | //echo -a %theme1 

the bits you would edit are:
set %theme1 $rainbowtext(¯·.¸¸¸.·´¯·.¸¸¸.->)
set %theme2 $rainbowtext(<-.¸¸¸.·´¯`·.¸¸¸.·´¯)

that would edit the start and end of the tags.

if you would like some more help, or have any questions, just send me a PM.
or you can send me some examples of themes you would like and i will replace the current themes with yours and send it to your PM.

thanks.