I have accomplished this by using a rich text field and compiling the HTML in an external file and importing it into the rich text field.
For Example I have a field on my form which is text called HTMLEntry and a rich text field called HTMLDisplay. I use the following lotusscript in the Queryrecalc of the form:
Dim s As notessession
Dim db As notesdatabase
Dim doc As NotesDocument
Dim fileNum As Integer
Dim fileName As String
fileNum% = Freefile()
fileName$ = {test.html}
Set doc = Source.Document
Open fileName$ For Output As fileNum%
Forall x In doc.HTMLEntry
Print #fileNum%, x
End Forall
Close fileNum%
Source.gotofield "HTMLDisplay"
On Error Resume Next
Source.selectAll
On Error Goto 0
Source.import "html", filename$
Kill filename