SOLVED! Code below.
Hope it saves some other poor soul from brain damage!

' This extracts the Proxy Connector GUID from the SQL result "SELECT Object_ID, Classifier_guid FROM t_object WHERE Object_ID = objectID"
function GetProxyConnectorGUID(objectID)
dim regExpr
dim matchPattern1
dim matchPattern2
dim matches
dim match
dim token
dim proxyString
dim sql
set regExpr = new RegExp
regExpr.IgnoreCase = true
regExpr.Global = false
sql = "SELECT Object_ID, Classifier_guid FROM t_object WHERE Object_ID = " & objectID
matchPattern1 = "<Object_ID>" & objectID & "</Object_ID><Classifier_guid>{[a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12}}</Classifier_guid>"
matchPattern2 = "{[a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12}}"
proxyString = Repository.SQLQuery(sql)
regExpr.Pattern = matchPattern1
Set matches = regExpr.Execute(proxyString)
if( matches.Count > 0) then
For Each match in matches
token = Mid(proxyString,match.FirstIndex + 1, match.Length)
Next
else
GetProxyConnectorGUID = ""
Exit Function
end if
regExpr.Pattern = matchPattern2
Set matches = regExpr.Execute(token)
if(matches.Count > 0 ) Then
for each match in matches
GetProxyConnectorGUID = Mid(token,match.FirstIndex + 1, match.Length)
next
Else
GetProxyConnectorGUID = ""
End if
end function