maulei the following is an extract from my trigger.ini i use it to accept party invites and invite ppl not in party. i forget which part is which i did this a while ago but part of it may help in what packets you need. 

[invite] 
0=r 8bXXXXXXXX02 send 5e08XXXXXXXX 
1=r 8bXXXXXXXX00 send 5e06XXXXXXXX 
2=r 75XXXXXXXXffff********01** send 5e06XXXXXXXX 


i think 
0=accept an invite 
1=invite all in room as they join 
2=invite a person not in party