Application Express :: Shuttle / How To Reference Selected Items On The Right Side

I have a simple shuttle:

1 Adam
2 Baker
3 Charlie
4 Delta
5 Echo
6 Foxtrot

Select Name D, UserID R from UserTable

The values are stored in a VARCHAR2 field MULTI_USER (for example 1:2:4:6) When I want to get the names back from the selected item, how do I reference the colon-separated items?

For example:

Select Name from UserTable
where UserID in (select MULTI_USER from MULTI_USER where MULTI_USER_ID = 1)

should return:

Adam
Baker
Delta
Foxtrot